AudioCodes MP-124 User Manual page 413

SIP User's Manual
For example:
INFO sip:5001@10.33.2.36 SIP/2.0
Via: SIP/2.0/UDP 10.33.45.65;branch=z9hG4bKac2042168670
Max-Forwards: 70
From: <sip:5000@10.33.45.65;user=phone>;tag=1c1915542705
To: <sip:5001@10.33.2.36;user=phone>;tag=WQJNIDDPCOKAPIDSCOTG
Call-ID: AIFHPETLLMVVFWPDXUHD@10.33.2.36
CSeq: 1 INFO
Contact: <sip:2206@10.33.45.65>
Supported: em,timer,replaces,path,resource-priority
Content-Type: application/x-detect
Content-Length: 28
Type= CPT
SubType= SIT-IC
The X-Detect event notification process is as follows:
1. For IP-to-Tel or Tel-to-IP calls, the device receives a SIP request message (using the
X-Detect header) that the remote party wishes to detect events on the media stream.
For incoming (IP-to-Tel) calls, the request must be indicated in the initial INVITE and
responded to either in the 183 response (for early dialogs) or in the 200 OK response
(for confirmed dialogs). For outgoing calls (Tel-to-IP), the request may be received in
the 183 (for early dialogs) and responded to in the PRACK, or received in the 200 OK
(for confirmed dialogs) and responded to in the ACK.
2. Once the device receives such a request, it sends a SIP response message (using the
X-Detect header) to the remote party, listing all supported events that can be detected.
The absence of the X-Detect header indicates that no detections are available.
3. Each time the device detects a supported event, the event is notified to the remote
party, by sending an INFO message with the following message body:
•
Content-Type: application/X-DETECT
•
Type = [CPT | FAX | PTT...]
•
Subtype = xxx (according to the defined subtypes of each type)
Below is an example of SIP messages implementing the X-Detect header:
INVITE sip:101@10.33.2.53;user=phone SIP/2.0
Via: SIP/2.0/UDP 10.33.2.53;branch=z9hG4bKac5906
Max-Forwards: 70
From: "anonymous" <sip:anonymous@anonymous.invalid>;tag=1c25298
To: <sip:101@10.33.2.53;user=phone>
Call-ID: 11923@10.33.2.53
CSeq: 1 INVITE
Contact: <sip:100@10.33.2.53>
X- Detect: Request=CPT,FAX
SIP/2.0 200 OK
Via: SIP/2.0/UDP 10.33.2.53;branch=z9hG4bKac5906
From: "anonymous" <sip:anonymous@anonymous.invalid>;tag=1c25298
To: <sip:101@10.33.2.53;user=phone>;tag=1c19282
Call-ID: 11923@10.33.2.53
CSeq: 1 INVITE
Contact: <sip:101@10.33.2.53>
X- Detect: Response=CPT,FAX
INFO sip:101@10.33.2.53;user=phone SIP/2.0
Via: SIP/2.0/UDP 10.33.2.53;branch=z9hG4bKac5906
Max-Forwards: 70
From: "anonymous" <sip:anonymous@anonymous.invalid>;tag=1c25298
To: <sip:101@10.33.2.53;user=phone>
Call-ID: 11923@10.33.2.53
Version 5.8 413
9. IP Telephony Capabilities
September 2009