[cisco-voip] Cisco's G729

[Wes Sisk]

We do multiple, it really depends on the endpoint.  Some of your 
verbiage looks CTI related, so I'm going to assume that is the interface 
you are trying to use.

Most of the ipphones register capabilities that include all variants of 
g.729.  Example of a 7960 registration:
09/22/2006 09:35:55.594 CCM|StationInit: (0000189) CapabilitiesRes 
capCount=7 caps= 25(120) 4(40) 2(40) 15(60) 16(60) 11(60) 12(60) 
|<CLID::496_Evoice-R5-CM1><NID::172.18.110.96><CT::1,100,119,1.1257817><IP::14.48.24.12><DEV::SEP000A41F97CC4>

This decodes to:
25(120) wideband
4(40) 711ulaw
2(40) 711alaw
15(60) 729b
16(60) 729ab
11(60) 729
12(60) 729a

from:
typedef enum {
    Media_Payload_NonStandard = 1,
    Media_Payload_G711Alaw64k = 2,
    Media_Payload_G711Alaw56k = 3,      // "restricted"
    Media_Payload_G711Ulaw64k = 4,
    Media_Payload_G711Ulaw56k = 5,      // "restricted"
    Media_Payload_G722_64k = 6,
    Media_Payload_G722_56k = 7,
    Media_Payload_G722_48k = 8,
    Media_Payload_G7231 = 9,
    Media_Payload_G728 = 10,
    Media_Payload_G729 = 11,
    Media_Payload_G729AnnexA = 12,
    Media_Payload_Is11172AudioCap = 13,
    Media_Payload_Is13818AudioCap = 14,
    Media_Payload_G729AnnexB = 15,
    Media_Payload_G729AnnexAwAnnexB = 16,
    Media_Payload_GSM_Full_Rate = 18,
    Media_Payload_GSM_Half_Rate = 19,
    Media_Payload_GSM_Enhanced_Full_Rate = 20,
   Media_Payload_Wide_Band_256k = 25,
    Media_Payload_Data64 = 32,
    Media_Payload_Data56 = 33,
    Media_Payload_GSM = 80,
    Media_Payload_ActiveVoice = 81,
    Media_Payload_G726_32K = 82,
    Media_Payload_G726_24K = 83,
    Media_Payload_G726_16K = 84,

Next is what ccm.exe considers as a 'match' between endpoints.  CCM 
matches based on the enum values above.  If it cannot find an enum 
match, then it generates a 'codec mismatch'.  If ccm finds a codec 
mismatch and cannot find a transcoder the default behavior is to connect 
the 2 endpoints, telling each to use their preferred codec which has 
bandwidth utilization less than the limit configured in Regions for 
callmanager.  There are a few interesting scenarios for h.323 - see the 
CM service parameter "Stirp G.729 Annex B (Silence Suppression) from 
Capabilities".  Also see CSCse92656 for one known sub-optimal endpoint.

/Wes

Paul Yago wrote:
> Does anyone know what version of G729 that Cisco is using?
>
> I'm registering a terminal with CiscoG729MediaCapability, but I'm not
> sure if they're using G729AB or G729A. 
>
> If they are using G729AB and my terminal is using G729A, will the other
> Cisco terminal downgrade to G729A?
>
> I'm also curious about G729CISCO7960 if anyone has some insight?
>
> Thanks,
> Paul 
>
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