World's First Voice Call From a Free GSM Stack

zycx writes "As Dieter Spaar has pointed out in a mailing list post on the OsmocomBB developer list, he has managed to get a first alpha version of TCH (Traffic Channel) code released, supporting the FR and EFR GSM codecs. What this means, in human readable language: He can actually make voice calls from a mobile phone that runs the Free Software OsmocomBB GSM stack on its baseband processor. This is a major milestone in the history of the project."

GSM Full Rate patent

[tepples]

I thought the GSM voice codecs were patented by Philips, as described in this page about an otherwise Free implementation of GSM FR [quut.com].

Re:Pardon me, but....

[pyr0r0ck3r]

If I'm reading correctly, yes, eventually you could roll your own phone using completely open source stuff - hw and sw. What I'm less clear on is how the signal is being carried. Granted, I didn't read too in depth, but you still need a carrier to allow your phone on their network, no?

Re:Pardon me, but....

[Gruturo]

You must have GSM confused with CDMA2000. In GSM, as I understand it, carriers don't allow handsets on their network; they allow SIMs on their network.

Not quite. The phone has to be allowed as well, its maker and model are sort of embedded in its IMEI and there are blacklist (not just for stolen handsets, but also for models with critical radio flaws which would not work or even disrupt the network in their vicinity while operating).

Re:GSM Full Rate patent

[GNUALMAFUERTE]

It is in fact the main codec used in most of my Asterisk systems. The implementation is 100% Free Software. Is it patent-free? No. But nobody has sued anybody so far, mainly because the big guys don't see its use in VoIP as a threat to their big-ass systems used in GSM networks. Now, this might be a different situation.

Re:IMEI blacklisting practices

[Gruturo]

The white/black/grey lists are held in the EIR (Equipment Identity Register), which may or may not exist at all (it's optional, some providers don't have one) and is sometimes integrated within the HLR

This is an explanation (a bit dated, but still) of how to decode manufacturer code, country code, approval code etc from the IMEI: http://www.cellular.co.za/ieminumbers.htm [cellular.co.za]

More info (just relevant stuff which came up googling "imei hlr eir"):
http://www.linkedin.com/answers/technology/wireless/TCH_WIR/612218-35166861 [linkedin.com]
http://www.linkedin.com/answers/technology/wireless/TCH_WIR/608687-35166861 [linkedin.com]
http://www.wordiq.com/definition/HLR#EIR [wordiq.com]

Brief description of the (global?) IMEI DB at the gsmworld site: http://www.gsmworld.com/our-work/programmes-and-initiatives/fraud-and-security/imei_database.htm [gsmworld.com]

Re:Pardon me, but....

[Anonymous Coward]

The GSM frequency bands are licensed spectrum. You can not legally operate a DIY device on these frequencies without prior approval of the license holders. (There is a loophole: some of the frequencies used for GSM in Europe overlap with amateur radio frequencies in the US, but then you have to operate your own "network" as well, not just the handset.)