09-03-2008 07:40 AM - edited 03-15-2019 01:01 PM
Hi,
My setup is as follows:-
CUCM--> SIP TRUNK --> CUBE --> SIP --> Service Provider
The CUCM SIP is configured for early offer with MTP checked.
MY CUBE config is as follows:-
voice service voip
address-hiding
allow-connections h323 to h323
allow-connections h323 to sip
allow-connections sip to h323
allow-connections sip to sip
no supplementary-service h450.2
no supplementary-service h450.3
no supplementary-service h450.7
supplementary-service media-renegotiate
supplementary-service ringback h225-info
redirect ip2ip
h323
emptycapability
sip
bind control source-interface GigabitEthernet0/0
bind media source-interface GigabitEthernet0/0
early-offer forced
midcall-signaling passthru
g729 annexb-all
sccp ccm group 2
associate ccm 2 priority 1
associate profile 1 register CUBEXCODE
keepalive retries 1
keepalive timeout 10
switchover method immediate
switchback method immediate
dspfarm profile 1 transcode
codec g711ulaw
codec g729ar8
codec g729r8
maximum sessions 24
associate application SCCP
dspfarm profile 4 mtp
codec g711ulaw
maximum sessions software 500
associate application SCCP
!
dspfarm profile 5 mtp
codec g729r8
maximum sessions software 500
associate application SCCP
!
dspfarm profile 6 mtp
codec g729ar8
maximum sessions software 100
associate application SCCP
dial-peer voice 200 voip
description ** outgoing call to CUCM **
destination-pattern 44T
session protocol sipv2
session target ipv4:x.x.x.x
dtmf-relay rtp-nte digit-drop
codec transparent
!
dial-peer voice 300 voip
description ** incoming dial peer **
session protocol sipv2
incoming called-number .
dtmf-relay rtp-nte digit-drop
codec g711ulaw
!
dial-peer voice 400 voip
description ** outgoing call to SIP Provider **
destination-pattern 9T
session protocol sipv2
session target ipv4:x.x.x.x
dtmf-relay rtp-nte digit-drop
codec transparent
I can make G711 calls in and out which always invoke an MTP.
All my G729 calls never invoke an MTP but invoke a transcoder instead. I can transfer these calls to G711 phones and vice versa.
My question is, is this normal behaviour?
Thanks,
09-03-2008 07:55 AM
SIP Early Offer is restricted for G711 only
SIP negotiates media exchange via Session Description Protocol (SDP), where one side offers a set of capabilities to which the other side answers, thus converging on a set of media characteristics. SIP allows the initial offer to be sent either by the caller in the initial INVITE message or, if the caller chooses not to, the called party can send the initial offer in the first reliable response. By default, Unified CM sends the INVITE without an initial offer, and it requires MTP resources to send the offer in the INVITE. Note that this initial offer is limited to the G.711 codec only.
Also note that MTP resources are not required for incoming INVITE messages, whether or not they contain an initial offer.
For the G729 calls, are they incoming from CCM to CME or viceversa?
Thanks
09-04-2008 12:39 AM
Thanks for the reply.
The G729 and G711 phones are on the same CUCM 6.1 cluster but in different regions.
Here is a show sccp connections for both a G729 and G711 outgoing call from CUCM:-
sess_id conn_id stype mode codec ripaddr rport sport
33555870 33564521 xcode sendrecv g729 172.30.15.11 29552 17898
33555870 33564519 xcode sendrecv g711u 10.25.0.50 17490 16738
sess_id conn_id stype mode codec ripaddr rport sport
33555871 33564534 mtp sendrecv g711u 172.30.15.20 24664 18662
33555871 33564533 mtp sendrecv g711u 10.25.0.50 16842 19502
AS you can see G711 invokes an MTP, early offer call, whereas G729 doesn't. I can understand the point that a G729 call will need a transcoder to talk G711 but is the transcoder also acting as an MTP and sending the invite with early offer?
Here is my debug ccsip message and below is the first sdp message for a G729 call:
v=0
o=CiscoSystemsCCM-SIP 2000 1 IN IP4 10.25.0.11
s=SIP Call
c=IN IP4 10.25.0.50
t=0 0
m=audio 16682 RTP/AVP 0 101
a=rtpmap:0 PCMU/8000
a=ptime:20
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
For G729 I would have expected to see both a transcoder and MTP being used to set up the call so I am a bit confused as to what is going on and whether this config is scalable?
Thanks,
09-04-2008 07:16 AM
Yuko,
What your are seeing is the expected behavior. In CUCM 6.x, SIP trunks only support G711a/ulaw with pre-allocated MTP.
In the CUCM 7.x, SIP Trunk will allow early-offer calls (calls with pre-allocated MTP) to be initiated with low bandwidth codecs such as G.729.
Here's the Release Note of CUCM 7.0 that calls out the enhancement in this version:
* Support for G.729a and G.729b Codecs Over SIP Trunks
G.729a and G.729b are low-bandwidth codecs that can be used for calls that are initiated over SIP trunks. Be aware that this feature is required for endpoints that do not support delayed media calls and do not want to use a higher-bandwidth codec, such as G.711.
Because an MTP needs to be pre-allocated for early-offer calls, you must configure an external MTP or transcoder device to use this feature. The software MTP does not support G.729 over SIP trunks.
Although this feature supports all four G.729 codecs (G.729, G.729a, G.729b, and G.729ab), the system cannot distinguish between G.729 and G.729a or between G.729b and G.729ab. Therefore, Cisco Unified Communications Manager Administration provides only two options for configuring these codecs on SIP trunks: G729/G729a and G729b/G729ab.
The G.729 codec over SIP trunks applies only to outgoing calls, and incoming calls are not affected. Be aware that the system does not support mid-call codec switching from G.729 to any other codec."
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/7_0_1/ccmsys/a08sip.html#wp1221209
Hope this helps.
Regards,
Michael.
09-04-2008 07:53 AM
Thank you both for your answers.
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