[Freeswitch-users] A primitive way of getting VoLTE recordings in FreeSwitch. Looking for better ideas.

[Francis]

One option is using mini-PCIe WAN cards that are VoLTE capable, using 
the I2S bus for bidirectional digital audio. The sticking point with 
this approach is that you need a backplain card with an I2S to USB 
bridge in order to capture the audio. This would probably work best with 
mod-gsmopen.

I searched high and low for such a thing, and managed to find one 
Russian firm that had a single slot device. The downside is that it is 
horrendously expensive (about $400 euros from memory), considering it 
only has about $5 worth of components on it. There are proprietary 
backplains, but so are their connectors, which limits you to their own 
line of daughter cards.

Francis


On 5/12/2016 9:29 PM, Oivvio Polite wrote:
> I'm building a call recording tool (outgoing calls only) where the prime considerations are 1) audio quality  and 2) ease of use.
>
> During the last years many mobile carriers have enabled VoLTE calling
> that operate at higher bitrates with better audio quality than
> traditional telephony.
>
> A common patterns seems to be that VoLTE is only enabled when the phone
> handsets on both ends supports it and both parties are on the same
> mobile carrier.
>
> To get that sweet HD audio in my call recordings I can't just run
> FreeSwitch with a regular SIP trunking provider. I've googled
> extensively and can't find any SIP trunking provider that claims VoLTE
> capability.
>
> A primitive way recording VoLTE calls with FreeSwitch would be to cook
> something together with mod_portaudio kind of like this:
>
> The user dials into FreeSwitch with a some custom HD audio client,
> probably using WebRTC. We capture this call leg at the server. Hooked up
> to the FreeSwitch box we have 3 audio cards. Connected to each audio card is a
> VoLTE capable cellphone on a diffrent mobile carrier (We pick the three
> most popular). The phones connect via the cellphone jacks. Each phone is
> also running a custom app that listens (via Wifi) for instructions from our FreeSwitch box.
>
> When the call arrives to FreeSwitch we check what carrier the the user
> is dialing. Hopefully one of our 3 connected phones also use that
> carrier. If so when instruct that phone to call the destination number
> and we connect the phone via mod_portaudio as the second leg of our
> call.
>
> This scheme as kind of Rube Goldberg and has many limitation.
>
> 1. If we want to support simultaneous calls on the same carrier we need
> more phones.
>
> 2. We loose audio quality in the recording when going from digital to
> analog.
>
> 3. Cellphones error prone, subject to freezes and what not. This is not
> something you want to put in a datacenter.
>
>
> So I'm wondering what other options might be for recording VoLTE calls.
>
>
> kind regards, Oivvio Polite
>
>
> _________________________________________________________________________
> Professional FreeSWITCH Consulting Services:
> consulting at freeswitch.org
> http://www.freeswitchsolutions.com
>
> Official FreeSWITCH Sites
> http://www.freeswitch.org
> http://confluence.freeswitch.org
> http://www.cluecon.com
>
> FreeSWITCH-users mailing list
> FreeSWITCH-users at lists.freeswitch.org
> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
> http://www.freeswitch.org