2G Fallback clarification?


levi

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So, VoLTE is IP-based like SIP?
That's what I think he's saying. It would make sense, conceptually and lexicographically; VoLTE is named after VoIP presumably, and LTE is as far as I recall entirely packet based, so LTE is an IP based technology. However, I'm not sure if you can run VoLTE entirely on the app CPU without support from the cell chip's CPU. I doubt it's technically impossible, more likely nobody will help you to do that or explain how.
 

AndiTheBest

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levi

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Found this german article how VoLTE works, as they hacked it.

https://www.golem.de/news/voice-over-lte-mobile-ip-telefonie-kann-abgehoert-werden-1512-118236.html
If you want a english version, this is a nice translation tool: https://www.deepl.com/translator
Interesting, and ignoring the underhand hacking side of it, seems VoLTE uses SIP to set up an RTP session - there are fairly mature linux libraries for those, so it doesn't sound impossible for us to code our own VoLTE app (for audio only in most cases probably) even though our cell chip doesn't support it. Probably needs some packet sniffing of legit call setups though to make sure we're behaving in an interoperable way with the rest of the 4G devices out there, but that's just what these guys have done.
 

AndiTheBest

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Interesting, and ignoring the underhand hacking side of it, seems VoLTE uses SIP to set up an RTP session - there are fairly mature linux libraries for those, so it doesn't sound impossible for us to code our own VoLTE app (for audio only in most cases probably) even though our cell chip doesn't support it. Probably needs some packet sniffing of legit call setups though to make sure we're behaving in an interoperable way with the rest of the 4G devices out there, but that's just what these guys have done.
The biggest problem is, you wont get the SIP-login account details from your provider without some hacking.
 

rygD

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It is all speculation until someone actually tries it.

Have any of the devs had a chance to try the mobile data module out? Have any of them tried to make a voice call?
I thought ED or someone said that both of those had been tested long ago. Pretty sure that was in Deutschland, not Oz, so still not exactly relevant to this discussion.
 

Silent-Hunter

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ED tested it. Since GSM protocol is the same in all countries, that means it should work everywhere. Only the frequencies are different.
 

Kotesh

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is PYRA now able to make calls , send sms to any type of network mobile phone?? As i am planning to buy it .. which can be used i both the ways.. so does it support to any type of network?
 

Silent-Hunter

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is PYRA now able to make calls , send sms to any type of network mobile phone?? As i am planning to buy it .. which can be used i both the ways.. so does it support to any type of network?
It won't work on Verizon, and it may or may not work on T-Mobile. A Cricket representative told me it would work after I described it to them, so it should work on anything that uses AT&T's network. It most likely will not work on Sprint.
[doublepost=1538979648,1538979605][/doublepost]I just hope it can use the 3G for voice calls. 2G no longer exists in the US.
 

levi

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]I just hope it can use the 3G for voice calls. 2G no longer exists in the US.
Really? They've dismantled all of the CDMA infrastructure, or do you just mean those few cities that got 2G GSM no longer have those networks? In the UK and much of Europe I guess where we never had CDMA, you can still buy a cheap 2G only phone, but in the US, GSM was largely an experiment mostly used by tourists to those cities from Europe I suspect.

Still, I remember when we were getting GPRS upgrades to our 2G services I remember some US-based people who lived out in the sticks that they hadn't got 2G/CDMA yet, and were still using analogue 1G services. The US is a big place and if you're anywhere away from the population centres, that kind of infrastructure investment was a long time coming. I guess that hasn't changed all that much in the intervening couple of decades, although the money's a whole different order of magnitude these days I suppose.
 

Silent-Hunter

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When they shut it off it seemed to be in lots of places. I live in a sparsely populated area, and we had it here.
 
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