02-24-2009 01:14 PM - edited 03-15-2019 04:26 PM
Hi,
-CUCM5.1
-CUBE, 12.4(15)T3
CUCM is connected to Carrier SBC via CUBE and have a question regards the MTP requirement.
The only requirement for MTP is to provide 'intercept message' by carrier when dial out a long distance call without '1' in front of 10 digit by mistaken. when I enabled MTP in CUCM SIP trunk interface, IP Phone can get proper intercept message from carrier as exmaple 'please add 1 in front of your dial destination' but 'air dead' if I disable MTP.
As I know its 'early media' feature and I found CUBE support the following,
!
voice service voip
early-offer forced
!
Is the carrier 'intercept message' accomplished by 'early media' feature in CUBE? My goal is eliminate MTP requirement in CUCM side.
Thanks in advance,
02-24-2009 01:46 PM
If you're using 'early-offer forced' I would upgrade to a 20T or 22T version first, as I don't believe it's officially supported until 20T (though the command exists)
Is this call flow SIP-SIP or H323-SIP?
You may want to check the restrictions to make sure the call flow you're wanting to do, as a number of the situations where you would want to use early-offer forced aren't supported call flows. Here's a link for SIP-H323:
http://www.cisco.com/en/US/docs/ios/voice/cube/configuration/guide/vb-gw-h323sip.html#wp1312731
The intercept message is actually just a 183/180 with SDP, which isn't properly heard unless you have early media configured.
hth,
nick
02-25-2009 05:45 AM
Hi Nick,
My case is sip-sip. can you give me some more detail about '183/180 with SDP' to communication to my carrier?
Thanks,
John
02-25-2009 06:02 AM
Hi John,
What happens is this:
CUCM--SIP leg 1---CUBE---SIP leg 2--Provider
We are doing delayed offer on leg 1 since this is an outgoing call and CUCM doesn't have MTP required checked. This means that we do not have media information on where to send audio for CUCM.
After we send the invite on leg 2, without media, we will receive a 18x message that is designed for ringtone. If the message does not have any media in it, we will normally generate ringback ourselves. If it does contain media, we will open our audio stream. Frequently when it has audio it is the provider sending audio that is similar to "Your call cannot be completed as dialed ...".
In this case, if we do leg 1 with delayed offer and leg 2 with early offer, you should be able to get the media from the provider since we will send media (SDP) in our invite.
hth,
nick
02-25-2009 06:05 AM
Thanks Nick,
I'll contact carrier with the information.
John
02-25-2009 06:40 AM
Hi John,
This isn't really something to contact the carrier about.
I would go to 12.4(20)T2 and try the early-offer forced command and see what results you get.
-nick
05-20-2010 06:42 AM
I work for ATT and we've deployed the CUBE for our/ATT's BVoiP/Flex SIP offering. From what i've experieinced the early offer - delayed offer issue is different then the early media - delayed media issue. When using Cisco SCCP phones you are forced to the delayed offer path and most carriers only support early offer. So, the early offer forced command will fix the EO-DO issue, but it does not fix the EM/DM/PRACK/183 issue. We worked with TAC and we were forced to "require MTP" for all calls using our SIP-CUBEs trunk. Bad news for us, we're currently running CUCM 6.X where only G711 is supported in this scenerio. In CUCM 7.X you can specifiy either G711 or G729.
Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: