[cisco-voip] Ulaw -Alaw and MTP resources

[Peter Slow]

it certainly looks like you're using Mu-law on that call leg. furthermore,
you stated that you are using an MGCP gateway.

What command did you use on the gateway that you were saying set it to
a-law?

I believe CUCM is solely responsible for instructing the MGCP GW as to the
voice codec to use, isnt it?

-Peter

On Mon, Nov 19, 2012 at 10:45 AM, abbas Wali <abbaseo at gmail.com> wrote:

> 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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