Early Offer vs Delay Offer How to identify them using RTMT How to activate Early Offer

One of the task is to identify SIP Trunking Troubleshooting using RTMT to determine if UDP port is being used and whether Early Offer or Delay offer is being used

SIP Delay Offer
In SIP Delayed Offer, the session initiator does not send its capabilities in the initial Invite but waits for the called device to send its capabilities first (for example, the list of codecs supported by the called device, thus allowing the calling device to choose the codec to be used for the session).
In SIP Delay Offer Invite Message does not contain SDP message.  Like below
Delay Offer message from RTMT (Real Time Monitoring Tool)
——————————————————————–
INVITE sip:01144204038804@172.16.1.103:5060 SIP/2.0
Date: Mon, 14 Nov 2011 03:23:26 GMT
Call-Info: ;method=”NOTIFY;Event=telephone-event;Duration=500″
Allow: INVITE, OPTIONS, INFO, BYE, CANCEL, ACK, PRACK, UPDATE, REFER, SUBSCRIBE, NOTIFY
From: “HQ Phone 2″ ;tag=4932d416-5429-4941-9e54-b619dbc00d2b-33611869
Allow-Events: presence, kpml
P-Asserted-Identity: “HQ Phone 2″
Supported: timer,resource-priority,replaces
Supported: Geolocation
Min-SE:  1800
Remote-Party-ID: “HQ Phone 2″ ;party=calling;screen=yes;privacy=off
Content-Length: 0
User-Agent: Cisco-CUCM7.1
To:
Contact:
Expires: 180
Call-ID: 28a1080-ec0189ae-f-c400d8e@142.13.64.12
Via: SIP/2.0/UDP 142.13.64.12:5060;branch=z9hG4bK2ee2f5080
CSeq: 101 INVITE
Session-Expires:  1800
Max-Forwards: 70
SIP Early Offer
In SIP Early Offer, the session initiator (calling device) sends its capabilities (for example, codecs supported) in the SDP (Session discovery protocol) contained in the initial Invite (thus allowing the called device to choose its preferred codec for the session).
Early Offer Message from RTMT
NOTICE that in initial INVITE message, SDP content is included
INVITE sip:01144204018804@172.16.1.103:5060 SIP/2.0
Date: Mon, 14 Nov 2011 03:22:07 GMT
Allow: INVITE, OPTIONS, INFO, BYE, CANCEL, ACK, PRACK, UPDATE, REFER, SUBSCRIBE, NOTIFY
From: “HQ Phone 1″ ;tag=4932d416-5429-4941-9e54-b619dbc00d2b-33611866
Allow-Events: presence, kpml
P-Asserted-Identity: “HQ Phone 1″
Supported: timer,resource-priority,replaces
Supported: Geolocation
Min-SE:  1800
Remote-Party-ID: “HQ Phone 1″ ;party=calling;screen=yes;privacy=off
Content-Length: 212
User-Agent: Cisco-CUCM7.1
To:
Contact:
Expires: 180
Content-Type: application/sdp
Call-ID: d3739f00-ec01895f-e-c400d8e@142.13.64.12
Via: SIP/2.0/UDP 142.13.64.12:5060;branch=z9hG4bK291884a035
CSeq: 101 INVITE
Session-Expires:  1800
Max-Forwards: 70
v=0
o=CiscoSystemsCCM-SIP 2000 1 IN IP4 142.13.64.12
s=SIP Call
c=IN IP4 142.13.64.11
t=0 0
m=audio 24606 RTP/AVP 0 101
a=rtpmap:0 PCMU/8000
a=ptime:20
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
How to Enable Early Offer on SIP Trunk.  It is configured on SIP Trunk
Delay Offer

In Delay Offer, SIP Trunk does not have MTP Checked.
Early Offer

in early Offer MTP must be checked.