GSM and Asterisk Integration?

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."

Comments

Already covered

[kevin_conaway]

See here

Short and long answer.

[wfberg]

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.

How about POTS?

[wintahmoot]

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?

Cheap Calling

[xtrvd]

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

Actually, it won't cost so much.

[Anonymous Coward]

GSM picocells will become available for home use. The problem, initially, is likely to be that although they'll talk IP over your broadband Internet connection they will be tied to a particular telco (who might even subsidise the hardware, I suppose). And unless the hardware is cryptographically authenticated, I don't expect it would be long before someone came up with an open source basestation controller, at which point what the OP wants would be possible. Spectrum licensing will be taken care of by the picocell vendor. The SIM card is a non-issue.

Use some imagination, all you naysayers.

[hklingon]

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).

If you were going to do it

[Stuart Ward]

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/ would be a good starting point, but you would need some specilised hardware to work at GSM frequencies.

Done that!

[directx]

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.