Mixed TCH/F and TCH/H issues

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Alexander Chemeris alexander.chemeris at gmail.com
Sat Sep 21 06:02:28 UTC 2013


On Tue, Sep 17, 2013 at 4:02 PM, Andreas Eversberg <andreas at eversberg.eu> wrote:
> the first call timed out, but i really don't the setup message. i
> suggest to retry that call. maybe it was an issue cause by radio
> interference (low MS power or high power, but too close to the bts).

Radio is fine and the issue was 100% reproducible.

> the audio of the second call is bad, so do you use rtpbridge feature of
> lcr? if so, how are the amr codecs define in openbsc.conf? be sure that
> they are equal for AFS and AHS, since a bridge does not transcode.

Rtpbridge was off.
Codecs where set to "fr afs ahs", since we don't want to cut off
phones without AMR support.

> also there is a general problem: the TCH/F is assigned for all MT calls
> from LCR->BSC. there are cases where we don't know the phone's codec
> support, unless we assign a channel and get setup information about
> supported codecs. but we cannot get setup message before assigning a
> channel. to solve this, late assignment is used. i suggest to use the
> jolly/new_handover branch. (you also need handover branch of lcr.) even
> with handover function disabled, it will do late assignment after codec
> negotiation.

We could try that, but I think the issue is elsewhere, as everything
works in single-trx mode.

-- 
Regards,
Alexander Chemeris.
CEO, Fairwaves LLC / ООО УмРадио
http://fairwaves.ru




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