[cisco-voip] Ulaw -Alaw and MTP resources

[abbas Wali]

Thanks Ryan

when i do a show call active voice brief i get the below

13EC : 361450 15:40:32.381 UTC Mon Nov 19 2012.1 +0 pid:0 Originate
connecting
 dur 00:01:13 tx:3639/582240 rx:3638/582080
 IP 172.30.176.162:28630 SRTP: off rtt:0ms pl:71930/0ms lost:0/0/0
delay:55/55/65ms g711ulaw TextRelay: off
 media inactive detected:n media contrl rcvd:n/a timestamp:n/a
 long duration call detected:n long duration call duration:n/a timestamp:n/a

13EC : 361449 15:40:32.379 UTC Mon Nov 19 2012.2 +10 pid:0 Originate  active
 dur 00:01:13 tx:3638/611184 rx:3651/584160
 Tele 0/0/0:15 (361449) [0/0/0.31] tx:73010/73010/0ms* g711ulaw* noise:-76
acom:2  i/0:-27/-57 dBm

does that mean its all ulaw?

and yes you are right we have checked that box for MTP req on the trunks.
this was to cover another issue with the lose of DTMF tones when we
upgraded from CM 7 to 8.5.

Thanks


On 19 November 2012 14:42, Ryan Ratliff <rratliff at cisco.com> wrote:

> If you were actually transcoding one of those legs would be doing alaw and
> the other ulaw.  What you see is two ulaw legs which means that your MTP is
> acting just like an MTP.  I assume by enabling the SIP trunk for MTP you
> mean you've checked the "MTP Required" box?  That box does just what it
> says it does, it forces an MTP for each call.
>
> You aren't wasting MTP resources for transcoding between alaw and ulaw,
> you are wasting them because you checked the box.
>
> I'd guess that you are actually using a uniform codec (look at the rtp
> streams on your mgcp gateway when a call is active and I'm sure you'll see
> they are ulaw there too) just not the codec you want.
>
> You've got two options for forcing ulaw vs alaw.  The first is a custom
> codec preference list with 711ulaw at the bottom of the list (you can't
> disable codecs this way, just prioritize them).  Look at System->Region
> Information->Audio Codec Preference List.  The second option is to disable
> g.711 ulaw via the service parameter "G.711 mu-law Codec Enabled".
>
> You may need to upgrade to get one or both of those options.
>
> -Ryan
>
> On Nov 19, 2012, at 8:40 AM, abbas Wali <abbaseo at gmail.com> wrote:
>
> Hi all,
>
> just to clairfy, we have confirgured PCM Type to ALaw (as in UK) on the
> MGCP gateways but all calls received shows ULaw on the phones.
>
> I believe our MGCP gateway is transcoding them as below
>
> Gateway3#show voice dsp active
>
> DSP  DSP                DSPWARE CURR  BOOT                         PAK
> TX/RX
> TYPE NUM CH CODEC       VERSION STATE STATE   RST AI VOICEPORT TS ABORT
> PACK COUNT
> ==== === == ======== ========== ===== ======= === == ========= == =====
> ============
>
>
> ----------------------------FLEX VOICE CARD 0 -----------------------
> -------
>                         *DSP ACTIVE VOICE CHANNELS*
> DSP    DSPWARE              VOX DSP                 SIG DSP          PAK
> TX/RX
> TYPE   VERSION    CODEC     NUM CH TS VOICEPORT SLT NUM CH TS RST AI ABRT
> PACK COUNT
> ====== ========== ========  === == == ========= === === == == === == ====
> ============
> C5510      27.3.1 *g711ulaw*  001 01 29 0/0/0:15  000 002 12 29   0  0
> 0  13359/13680
> C5510      27.3.1 g711ulaw  001 02 31 0/0/0:15  000 002 14 31   0  0
> 0    3707/3816
>
> The SIP trunks are enalbed to use MTP resources  and the MTP Preferred
> Originating Codec[image: Required Field] is set to ALaw.
>
> I think we are wasting alot of MTP resources converting from A to U. is
> there a way to use a uniform codec in CUCM 8.5.
>
> Many thanks
> --
> @bbas..
>
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>
>


-- 
@bbas..
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