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Communications Hardware Hacking

GSM and Asterisk Integration? 156

Posted by Cliff
MistabewM asks: "Would it be possible to place a GSM transceiver within you home that can be tied into Asterisk in a way that would allow you to place calls from your GSM phone across your VOIP connection or though your local landline? An analogous system is being introduced on airplanes that will allow passengers to use their GSM phones in flight. I feel this would be a fantastic hack and could even be scaled up to provide large areas of free GSM service."
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GSM and Asterisk Integration?

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    • by Anonymous Coward
      He wants it the other way around, and that is not possible. You can't just activate your own GSM micro-cell. It's a licensed band for which you don't have a license.
      • by Dare nMc (468959)
        >It's a licensed band for which you don't have a license.

        as long as your at a low enough power, and your not interfearing with anyones communication, you are allowed to. same as those ipod/radio transmitters to your car radio.

        I would say as long as their is no GSM availabilty where you want to deploy this, and a limited range, it would be legal. I say this because I have helped install a transmitter, for my company, with AT&T's approvel though, for a test.
      • i'm not a usian myself but isn't 900mhz an unregulated band in your country so you possiblly could make something legal that would work with tri-band phones (iirc the base station controls the transmit power of the handset too so it should be able to keep that within limits).
    • This is like attaching a cellphone to your asterisk. It allows you to make calls across the GSM network and to receive calls to the number programmed on the SIM card and pass them to the asterisk box.

      There have been some attempts to do what the parent is asking about, but I do not know of any that have been rolled out for public consumption.

      • The article explains how to do what the poster asked for: make a call on the cell phone and route it through asterisk. It looks like the GSM gateway acts as an extension in the Asterisk PBX network, so you should be able to do anything that a locally attached phone is permitted to do (based on configuration). That inclues placing outgoing calls on the land line.
        • Not really. The GSM gateway discussed is not a GSM cell - its just another GSM client. You can of course call it and be connected to your local PBX - but you'd do so using some GSM operator's cells, which is hardly what the post asked. You seem to be confusing GSM with peer-to-peer radio. I know peer-to-peer is all the rage now, but please, do get a clue.
          • He wants to "place calls from your GSM phone across your VOIP connection or though your local landline". You can do that with the gateway as described. Nothing is mentioned about setting up a private cell.

            And how am I confusing GSM with peer-to-peer radio? Why did you feel a need to be insulting, rather than provide useful information?
            • Nothing is mentioned about setting up a private cell.

              Well, not in those words. But he did ask about using his normal GSM handset which would connect to a GSM transceiver connected to his asterix pbx, in other words a private cell.
    • by Dare nMc (468959)
      Interesting, but thats the opposite of what the post requests. That allows you to use your cellphone minutes from you home phone.
      The poster wants to use their landline/sip minutes from their cell phone when at home.
    • I finally got a first post and didn't realize it...
  • Free? (Score:5, Insightful)

    by gtrubetskoy (734033) * on Friday August 19, 2005 @01:21PM (#13356368)

    Sounds like an interesting hack indeed, but I'm not sure how it will result in a free service. Someone needs to administer the Asterisk server, pay for electricity, the bandwidth to the server and lastly don't you need a license to use GSM frequencies? If you'd be willing to cover all these costs, then sure, it will be free. :-)
    • Re:Free? (Score:4, Insightful)

      by nacturation (646836) <nacturation&gmail,com> on Friday August 19, 2005 @02:10PM (#13356665) Journal
      Your post also described the price of air. Yes, breathing air is free, but as long as you're willing to expend the energy required to flex various muscles resulting in the lungs expanding and inhaling air. And you'll also need to drink water and ingest food -- which you'll need to purchase or grow. If you grow your own, you'll probably need to either purchase or fashion the tools required to till the soil and plant the seeds. So yes, air is free if you're willing to cover all those costs.
       
    • Re:Free? (Score:4, Funny)

      by lightspawn (155347) on Friday August 19, 2005 @02:14PM (#13356704) Homepage
      Someone needs to administer the Asterisk server, pay for electricity, the bandwidth to the server and lastly don't you need a license to use GSM frequencies? If you'd be willing to cover all these costs, then sure, it will be free.

      Sounds like a risky proposition... but it's his own asterisk.
    • Indeed. And even once you clear those obsticles you still must contend with [insert giant greedy GSM provider's name(s) here] setting a pack of flesh eating lawyers upon you. Seems to me this is better done currently with wifi and some of the wifi VOIP handsets coming down the pike (if not out already). And, there's still more unlicensed spectrum out there to play with so time will tell if someone will come up with a better free/low-cost alternative to current wireless telephony products.
    • Very true, but free wi-fi access points also cost money to setup and there are enough of those around. I'm not saying that those are proof that something like this will take off, I think it's at least possible.
  • by EvilMagnus (32878) on Friday August 19, 2005 @01:25PM (#13356394)
    , the search term 'GSM Picocell' turns up these guys [ipaccess.com] who appear to sell a GSM-to-IP product exactly like that.
  • Already covered (Score:5, Interesting)

    by kevin_conaway (585204) on Friday August 19, 2005 @01:25PM (#13356396) Homepage
    See here [slashdot.org]
  • by ReformedExCon (897248) <reformed.excon@gmail.com> on Friday August 19, 2005 @01:25PM (#13356397)
    But you're looking at some serious changes to your wireless hub. If you are asking, I doubt you'd be able to do it.

    That's not meant as a slight, but just the truth. It's a very difficult thing to set this up. It requires more than just running some daemon. It also requires authenticated sessions on the servers. If you aren't Ericsson, you aren't getting into the network.

    That isn't to say that you couldn't implement this yourself. Skype, for example, doesn't run across the traditional long distance network, but it provides long distance phone service over the Internet. If you are willing to dive headlong into a long and arduous development plan, sure, you could implement this.

    Don't hold it against me that I'm not holding my breath for this, though.
  • RF interference (Score:3, Insightful)

    by ALecs (118703) on Friday August 19, 2005 @01:26PM (#13356404) Homepage
    Hopefully this gateway can use a frequency that doesn't have harmonic interference with radio astronomy to communicate with the ground (or even better, the sky - via satellite).

    And also hopefully, the handsets will use low enough power that it doesn't result in the equivalent of a 35000-foot cell tower.

    http://www.spaceref.com/news/viewpr.html?pid=17017 [spaceref.com]

    • Maybe not though... maybe this would be a great idea for cell phone companies...

      If it works technologically (i.e. no doppler problems) having 35,000 ft cell towers which dont have to ugly the landscape would be great...

      Whey didnt they think of this earlier?
  • by Brento (26177) <brento@brentoz a r . c om> on Friday August 19, 2005 @01:27PM (#13356408) Homepage
    ...could even be scaled up to provide large areas of free GSM service.

    How exactly do you get large numbers of GSM transceivers for free? This sounds suspiciously like a dot-bomb business model. I mean, I'm willing to buy a wifi router and give away my internet connection because any tool with a wifi card can figure out how it works and take advantage of it. But buy a GSM transceiver, host an Asterisk server, and manage it all for strangers who walk past my house? What a tech support pain in the ass.
    • But buy a GSM transceiver, host an Asterisk server, and manage it all for strangers who walk past my house? What a tech support pain in the ass.

      Sure, but what if you run a company and want to un-wire your campus? Forget desk IP phones, just have a few picocells strewn about and have people use their own phones (or buy $20 GSM phones from some random reseller).
      • Sure, but what if you run a company and want to un-wire your campus?

        Commercial use of GSM frequencies requires a license from the FCC. It isn't an open frequency like 802.11b operates on.
  • A rephrase (Score:3, Funny)

    by DraconPern (521756) <draconpern@hotmai[ ]om ['l.c' in gap]> on Friday August 19, 2005 @01:28PM (#13356421) Homepage
    Let me rephrase the poster... ;-) Hello Slashdot, I want to start a mobile phone company with no money down. I am very poor but I want to provide GSM, voice mail, fax, voip, free calls, etc. Can you people help me?
  • Licensing (Score:3, Informative)

    by amembleton (411990) <aembleton @ b i gfoot.com> on Friday August 19, 2005 @01:30PM (#13356428) Homepage
    To legally set up a GSM transceiver you would need to purchase a licence. Well, I'm sure thats the case in most countries anyway.

    I know that the mobile phone companies in the UK spent a hell of a lot of cash to secure 3G licences, they wouldn't be too happy if you got to set up your own transceiver for free.

    Yes, I know a handset is a transceiver, but that probably comes under some kind of different licence.
    • By my understanding you are allowed to use a transceiver (your handset) because you pay money every month to the spectrum owner (your cell phone provider). So basically the provider is leasing the spectrum to you, but it still belongs to them. Or do they lesae it from the FCC and then sublease it to you?
    • That's not true, as of recently, in the UK. There's a small overlap between some of the unlicensed spectrum and that used by GSM phones (it was originally intended to protect 3G and GSM phones from interfering).
  • Just a quick search comes up with a few companies like www.ipscellular.com that makes custom gms and cdma equip that you could put togather with a system like that, I dont know about the free part though, seems like someone would have to be footing the bill.
  • by wfberg (24378) on Friday August 19, 2005 @01:32PM (#13356447)
    Short answer: No.

    Long answer: The main restriction here is the use of restricted frequencies, and some "minor" technical hurdles.

    while it's perfectly OK for you, as a lone individual, or a company, to operate a GSM handset, operating a base-station is another thing. First, you'd have to get your greedy paws on a basestation, then you'd have to make your own SIM cards (hijacking calls that should be on the regular operator's network is highly illegal (DMCA); there's all sorts of (broken) encryption going on), and you'd have to outfit phones with 2 SIM cards, switching from your own network to the other (which entails switching the phone off and on again) every time you enter or leave the building. (This is doable, but annoying).

    Now, assuming you don't want the legal hassles of paying for multi-million dollar cell network licenses, you could operate a "pirate" basestation on some frequencies that aren't used too much where you're at (you'd have to measure it through first).

    In other words; you're better off investing in a handset that does both GSM and DECT(or whatever you use for domestic wireless phones in the US) or even both GSM and WiFi. There aren't many of those (though BritishTelecom has announced their model), but there should be some out there.
    • while it's perfectly OK for you, as a lone individual, or a company, to operate a GSM handset, operating a base-station is another thing.

      While running a renagade cell tower isn't generally a viable option, if you command enough clout (i.e. a professional reputation and enough potential users) you can convince an existing cell carrier to put up a cell station on their network for your own private use.

      For example, Verizon put a cell station in an underground data center where I used to work. There would n

  • If you were close to a "free" or open picostation like the one ipaccess.com has, would it then be free minutes then, or would the cellular company still ding you for using the frequency since the phone is registered to them?

    What are the costs on a system like this?
  • by Zarhan (415465) on Friday August 19, 2005 @01:33PM (#13356458)
    Ok, the equipment:

    One microcell, coming right up.

    Ok, simple omnidirectional antenna.
    Then you need the base station that drives that antenna.
    Then you need the base station controller that drives the base station.
    Then you need MSC (mobile switching center...) that actually gets the calls from the base station and forwards it accordingly to an SS7 network.
    Then you need to set up Asterisk to talk to that SS7 network and grab your phone calls.
    And all the rest of the components that I have forgotten.. In effect, you need to become a full-blown telco, albeit with only one base station.

    All the equipment can be bought from Nokia, Ericcson or other mobile network vendors. Price range is not for home users.

    Then, you need to get a license to operate that basestation. 900/1800/1900MHz is a licensed band. This *might* be quite easy if the location is just a single cell.

    Anyway, then you need to apply for Mobile Network Identifiers (MCC + the rest) to distinguish yourself as a GSM operator, so when you search for networks with your GSM phone, you'll see your own network as one.

    Then you need to get a SIM Card to use with your phone that has access to your network. (Or, you may be able to set it to "open for all" mode).

    (Of course, if the question was simply if you can reaac GSM network via Voip and want to set up the gateway your own home, then that's easy, just plug a phone or wireless modem to your Linux box....but I was under the impression that this meant the ability to use your GSM phone as a "cordless phone".)

    With landline this is of course easy, all you need is a modem waiting for calls..
    • 900 is unlicensed, isn't it?

      850 is licensed, but as long as you have a quad-band phone.....
      • 900 is unlicensed in the US for certain uses, which do not include GSM. Unlicensed only means that the end-user doesn't need to get an FCC license (and learn morse-code!), but the equipment and use still has to comply with FCC rules. Check here [part-15.org].
        • I don't understand how it can be unlicensed for certain uses and not other uses.

          Do you mean it is not unlicensed for GSM because of power requirements?

          Or does GSM occupy more frequency space than is unlicensed in the 900 Mhz band?

          As long as you comply with all FCC rules, you should be able to do GSM in the 900 Mhz band.

          Not that it would necessairly be useful once you did, but still, one could do it, perhaps in your own home or something. I don't know much about any of this, however, so you're probably right
          • You don't need a license to operate on the band. Your equipment, however, must be certified to comply with the FCC section 15 rules.

            Google for "Tragedy of the Commons" if everyone were able to cook up wacky RF-based services, nobody would be able to use the spectrum at all -- its bad enough as it is.

            50 years ago, you could hear a 10,000 watt AM station for 1000 miles. Today, you're lucky to get 150.
    • You forgot about the HLR :)
  • May not be exactly what you're looking for, but I am investigating GSM solutions right now, for a slightly different reason: I want to make all my GSM-to-land calls appear "in the network", and eliminate the huge costs associated with cell-to-land calls. Here are a couple of links:
    http://www.westlakecommunications.co.uk/Bluetower. htm [westlakeco...ions.co.uk]
    http://www.qiiq.com/products/productsGoldenGatePRI GSM.htm [qiiq.com]
    http://www.telular.com/products/product_index.asp? tech=GSM [telular.com]
    http://www.mobilecomms-technology.com/contractor [mobilecomm...nology.com]
  • How about POTS? (Score:3, Interesting)

    by wintahmoot (17043) on Friday August 19, 2005 @01:46PM (#13356538) Homepage
    Is there an EASY way to route from POTS to VoIP and back? I'd like to be able to call my home phone number from my cell, and then punch in a number which will be dialed via VoIP.

    The same goes for the other way around, when somebody calls my VoIP number, I'd like it to forward the call using my home phone line to my cellphone.

    I know that this is possible, but what's the easiest way to achieve it?
    • Somehow related to what you are asking for: I have a cell phone, with $10/month unlimited data plan, on which I have installed Skype. I have reasons to believe that any other VoIP soft-phone solution could be installed, if an appropriate client for the platform existed, thus the "hope" into VoIP that you are asking for.

      My provider could probably never figure out (if he would ever care) how I could keep a consulting business on a minimal dial plan ;)
    • Cheap Calling (Score:5, Interesting)

      by xtrvd (762313) on Friday August 19, 2005 @02:03PM (#13356628)
      I have an 'unlimited incoming local calls' feature on my phone, combined with 100 minutes (practically nothing) of outbound calling per month. I pick up my mobile, dial a number, punch in an extension, and then hang up. This process takes about 5-6 seconds.
      After I hang up, my home phone number calls my mobile phone and gives me an IVR (Voice Menu) where I can dial out using VOIP long-distance.

      The call is free, because it looks like an incoming call from my home, but I'm using my home line to make the VOIP call outbound from my cell phone.

      This is my trick; the only inconvenience is that you have to dial a number BEFORE you make outbound calls, but I can live with it. =)

      -Jesse
      • this is pure genius. i am going to go out and by a cellphoen this weekend to do this with.
      • Are you using Asterisk? If so, would you mind posting your dialplan and associated config information? I have a Nextel phone with free incoming and have thought about doing something similar.

        The other method I thought of for doing this is a WAP page that I can load on my phone's web browser with a simple form. Type in the number, the cell phone rings and then the call is placed to the remote party. This would prevent your "have to dial a number before you make your outbound call" annoyance.

        Jeremy
        • Re:Cheap Calling (Score:5, Informative)

          by xtrvd (762313) on Friday August 19, 2005 @07:22PM (#13359030)
          The parts of my extensions conf that you need to know are:
          exten => 123,1,Answer
          exten => 123,2,System(/etc/asterisk/callme)
          exten => 123,3,Hangup

          The 'callme' file is a bash script that looks alittle something like this:

          #!/bin/bash
          sleep 4
          umask 000
          (
                          echo "Channel: IAX2/loginname:password@provider/8885555555"
                          echo "Callerid: Magic"
                          echo "MaxRetries:1"
                          echo "RetryTime: 10"
                          echo "WaitTime: 30"
                          echo "Context: internal"
                          echo "Extension: 444" ; the extension of the IVR
                          echo "Priority: 1"
          ) > /var/spool/asterisk/outgoing/callme.call

          That will wait for 4 seconds before calling the mobile so that you have a chance to hang up after you press '123' after calling in.

          In my example, you use an IVR with the number '444' which forwards to the IVR 'callme-menu' presented as soon as you pick up your cell, here's the part from my extensions for that:

          [callme-menu]
          exten => s,1,Answer ; Answer the line
          exten => s,2,DigitTimeout,5 ; Set Digit Timeout to 5 sec
          exten => s,3,ResponseTimeout,7 ; Set response timeout to 7 sec
          exten => s,4,Wait(2) ; Wait two seconds to make sure speaker is at ear
          exten => s,5,Background(what-are-you-wearing) ; Greeting call
          exten => _9X.,1,SetCallerID(JESSE)
          exten => _9X.,2,Background(pls-wait-connect-call)
          exten => _9X.,3,Goto(outbound,${EXTEN:1},1)
          exten => _9X.,4,Congestion

          I hope this helps you. I think I'll put it on the wiki this weekend so more people can screw the system.

          =)

          -Jesse
          • Thank you very much. I'll try to get the WAP page functionality working and I'll let you know if I get it to work decently.

            Jeremy
    • Simple, purchase a Sipura 3000. You can register it with Free World Dialup, voicepulse, NuFone, or Asterisk (or anything else that speaks standard SIP). It allows you to dialin from the PSTN and then via a password or not get access to a VOIP network. Very configurable...

      Hope this helps.
    • make a GOTOIF statement that reads the callerid of your cell and sends you to another context/menu

      something like this..

      exten => s,1,Zapateller(answer|nocallerid)
      exten => s,2,Wait(2)
      exten => s,3,Answer
      exten => s,4,PrivacyManager
      exten => s,5,lookupCIDName
      exten => s,6,lookupBlacklist
      exten => s,7,GotoIF($[${CALLERIDNUM} = xxxxxxxxxx]?some:other:context,s,1:8)
    • Yes. Absolutely. Asterisk [asterisk.org] is your friend, and can easily do this.

      More people should spend some time nerding out with Asterisk and other free VOIP technology. It's way cool.

  • by chill (34294) on Friday August 19, 2005 @01:47PM (#13356546) Journal
    http://store.voxilla.com/customer/product.php?prod uctid=16136 [voxilla.com]

    Basically, get two phones and a plan with free mobile-to-mobile minutes. Leave one at home in the base station and connect it to Asterisk with a DTA.

    Call home with your mobile, then call again from there to where ever via VoIP. Basically a cell-to-VoIP gateway.

    There is a FAQ somewhere around that explains exactly how to do this.

      -Charles
  • by squiggleslash (241428) on Friday August 19, 2005 @02:06PM (#13356642) Homepage Journal
    Yes and No.

    No, in most juristictions, it's illegal to operate your own base station on any of the frequencies supported by GSM (850, 900, 1800, and 1900MHz, I think 450MHz is coming on stream in various places too. But that's also a problem.)

    However, there's a new system called UMA that tunnels the GSM protocols through an IP connection provided by either an 802.11 base station or some form of bluetooth receiver. The system has some limitations in its present form, the major ones being:

    1. Few carriers support it. In the US, practically none do.
    2. Few phones are available that support it. In theory, most bluetooth supporting phones could be made to support it with a firmware update. But that's not likely to happen. I know the UK version of Motorola's RAZR V3 now supports the feature, but it's in a small class of phones and the US version doesn't yet.
    3. Each "base station" has to be registered by the GSM operator, I have NO IDEA why. That means plain old open WAPs in malls wouldn't provide a solution to poor coverage inside them, for instance, and you (probably) couldn't use the system to defeat roaming charges by using a Starbucks WiFi connection in the UK with your Cingular phone.
    It also isn't exactly what you've asked for. It's largely seen as a system to help phone users improve their reception and reduce their dependence on the capacity of the wide range GSM network. It's designed to be seamless, you can start a call on the 802.11 network, step "out of range", and the call will transfer to a nearby GSM tower just as it would if you were going out of range of any other GSM tower.

    By comparison, it looks like you're just after a way to turn a GSM phone into a cordless handset.

    I've covered the system in my journal [slashdot.org]. It'd be nice to see it better supported, and to see other standards also adopt it such as the CDMA ones. Much of the issues of capacity and poor reception would be dealt with if the system became a standard part of most people's mobile phones.

  • Relevant Suggestion (Score:2, Informative)

    by dingletec (590572) *
    There is a device called cellsocket that my company uses to connect regular analog telephones up to cellphones. You pick up the phone, hear a dial tone, then dial as you normally would, but it uses your cellphone for the connection. You could possibly connect something like this to your house POTS wiring and use your regular phones in the house while your cellphone sits and charges.

    As far as making VOIP calls, there is the Sipura-3000 which mentions something similar to what you are asking. The manual
  • Would it be possible to place a GSM transceiver within you home

    This sounds like nothing more than a DIY micro-cell, for people who feel the cell towers provided by the phone company aren't already good enough.

  • When I worked for L3 (Level 3) almost 5 years ago, we had implimented a similial solution that would let your GSM cell phone turn into a local extension on the PBX. Thus allowing to make various calls such as VoIP, internal (calling another extension) and outgoing calls. Granted I never was around the equiptment, so I couldn't tell you what it was, but just the fact that it was available many moons ago.
    • by maxrate (886773)
      I remember NOKIA had a solution in '99 for this. We didn't go for it because our office only had 15 people, but it was neat-o.

      You walk into the building and your mobile would switch to pbx mode - local extension at your desk mobile style. Low output power too - no brain tumours.

    • I recall visiting IBM's offices in Warwick, UK around '97 or '98; they had something similar then. It certainly isn't a new idea.
  • This article nerdy... ...even by Slashdot standards.
  • "Would it be possible to place a GSM transceiver within you home that can be tied into Asterisk in a way that would allow you to place calls from your GSM phone across your VOIP connection or though your local landline? "

    Now seriously...listen to yourself...how do you look yourself in the mirror each morning?

  • Why waste all that money on a GSM base station, when a WiFi/3G phone [google.com] is so much cheaper? And has 10-1000x the bandwidth, with existing protocols, interop'ing with public/friends' hotspots? The Asterisk integration still makes perfect sense, especially when virtualizing one's telecom out of a home server.
  • I have just integrated an asterix into "GSM":

    GS*M

  • The problem with PicoCell and Nanocell is twofold - cost and SIP Compatibility. What you want is something like this device from 2N.
    Voice Blue Lite [2n.cz]

    This device is supposed to cost about 3500$ USD (only reference I could find online), and creates a mini-gsm cell backed by a SIP provider. This device has been tested with Asterisk.
    • > and creates a mini-gsm cell backed by a SIP provider.

      Untrue. Reread the documentation provided on the webpage. This device is a client to the GSM network of your provider, like your mobile phone. It will connect to the network and receive calls and distribute them to local or remote (via sip) phones, and vice versa allows to call out over the gsm "phone".
  • As many others have pointed out, running your own GSM network is pretty much out of the question, since you wanted to save some money, not brun through a couple million.

    Unsurprisingly, some vendors have already trialled products that allow a GSM handset to be used as a local wireless phone, too. I remember Sagem having one that would double as a DECT handset if in range of the DECT base station, but continue to be booked into the GSM network. More recently, people have put SIP and Skype software on smart

  • by hklingon (109185) on Friday August 19, 2005 @03:40PM (#13357498) Homepage
    This is a general reply to all the +5 comments that are saying stuff like 'picocell' and 'well, you could modify xyz and ... but you'd still need to sign on to the provider's network'

    Look. It is very simple. Take advantage of the 'free calling to other members' most providers offer. I.e. Add a tmobile phone to your plan and make your plan a shared-minutes plan. Get free tmobile to tmoble. Make liberal use of the headset port.

    Take ANY GSM phone that has a good USB and headset interface. A bit of straightforward hacking (as asterisk already supports sound cards for in and outbound sound channels) gets the headset connected to the asterisk box. Now all you need to do is press buttons on the phone.

    Enter the usb interface, basically a com port in disguise. ATDT ring a bell? A lot of phones support this last time I checked. Most motorola phones for sure so you can dial folks in your bluetooth organizer with the click of a wand. Instead, you can just have Asterisk decode the DTMF and (with a dialing rule) when you've dialed 7 or 10 digits, it will encode it as an ATDT string, send to the phone, and connect the audio channels.

    Ta-Da. It works, by the way (though instead of a USB interface I just hacked the keypad interface as it was more convenient for me to do that with the equipment I have. My interface is on a com port and tied together with an Atmel microcontroller FYI I did this initially because I was annoyed I had to pay to call to check my VM on my office phone).

  • Wasn't it Nathan Hale who said, "I regret only that I have but one asterisk for my country"?
  • The way to do it would be to use a software defined radio (SDR), I know that several manufactors are looking to use SDR for their latest UMTS (3G) basestations, and eventually for the phones as well. http://www.gnu.org/software/gnuradio/ [gnu.org] would be a good starting point, but you would need some specilised hardware to work at GSM frequencies.
  • Done that! (Score:2, Interesting)

    by directx (752946)
    We have one in the office right now. We have a Nokia GSM transceiver connected to the Asterisk PBX and we can call our VoIP numbers from our cell phones thru the Nokia - savings us a couple of pesos by having cell-to-cell calls instead of cell-to-landlines. The same goes true for VoIP calls to cell phones.
  • http://accessories.skype.com/item?SID=5d9ba1d6cf62 52723dd960807ee8ad5ac20:4515&sku=3045PH [skype.com]

    and btw, could you let me know how it goes ? I'd love to know how this thing performs ...

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