Monday, September 21, 2015

CUCM SIP Early Offer


By default CUCM uses SIP Delayed Offer. In order to enable Early Offer, use one of the following methods:

  1. MTP is required option should be selected on SIP Trunk. Then trunk will operate in Early Offer mode and will send SDP capabilities of the MTP device in initial INVITE message (IP, UDP Port, Codec Capabilities, etc). The MTP device will be allocated from the Trunk MRGL instead of the calling endpoint MRGL

KEEP REMEMBERING: By default if CUCM fails to allocate MTP, call will resume without MTP. This means that CUCM SIP Trunk will fallback to delayed offer. This service parameter can be changed.

TIP: In early offer, you can change the codec between alaw and ulaw (or G729 Annex-b and w/o Annex-b) using the option "MTP Preferred Originating Codec" under SIP Trunk. This won't overcome region config which should be G711 or G729.

  1. SIP Profile checkbox “Early Offer support for voice and video calls (insert MTP if needed)”.
    1. For calling endpoints that are capable of providing their details such as IP, UDP Port, Supported Codecs, MTP won't be inserted for outgoing call signalling
    2. For calling endpoints that aren't capable of providing their details such as IP, UDP Port, Supported Codecs, MTP will be inserted for outgoing call signaling and CUCM will include MTP details in the SDP of the initial INVITE
      1. MTP will be allocated from calling endpoint MRGL
      2. If failed, MTP will be allocated from outgoing trunk MRGL

Calling Device Type
Outgoing Trunk
MTP Inserted
SIP Phone
Early Offer SIP Trunk
No
New SCCP Phone
Early Offer SIP Trunk
No
Old SCCP Phone
Early Offer SIP Trunk
Yes
Early Offer SIP Trunk
Early Offer SIP Trunk
No
Delayed Offer SIP Trunk
Early Offer SIP Trunk
Yes
Slow Start H323
Early Offer SIP Trunk
Yes
Fast Start H323
Early Offer SIP Trunk
No
MGCP
Early Offer SIP Trunk
No


Method 1 vs. Method 2

  1. SIP Profile method support SRTP and Video calls since it supports MTP codec passthrough. This isn't support in Method-01 since MTP can be either G711 or G729.
  2. Less usage of MTP resources (only if needed)
  3. MTP is inserted from Calling endpoint instead of outgoing SIP trunk
at
Labels:

3 comments:

  1. Anonymous12:04 AM, February 08, 2016

    Very nice information and simple way to understand.

    Many Thanks!

    ReplyDelete
  2. Unknown4:29 AM, April 12, 2016

    Nice info. Easy to understand.

    ReplyDelete
  3. ravi11:10 PM, July 23, 2019

    when you say "send SDP capabilities of the MTP device in initial INVITE message " so what do you mean by MTP device .Can you please clear

    ReplyDelete

Subscribe to: Post Comments (Atom)

DNS Performance Troubleshooting

When you are troubleshooting internet performance, there are different parts of the connection should be verified:   ·         DNS Pe...

  • PxGrid Part # 3 - Troubleshooting FMC-ISE Identity Sync
    From FMC CLI, verify ISE integration status using the command   root@vFPMC:/etc/rc.d# cat /var/sf/run/adi-health $status = {      'ADI&#...
  • Enable ISE SSH Access
    If you missed enabling SSH access during the initial setup of ISE, you can enable it using console by pasting the command   service sshd enable
  • CUCM SIP Early Offer
    By default CUCM uses SIP Delayed Offer. In order to enable Early Offer, use one of the following methods: MTP is required ...