This blog is intended to help you understand the SIP DTMF Options supported by Cisco Unified Communications Manager (CUCM).
SIP DTMF options supported by CUCM:
DTMF can be sent either in band or out of band (OOB)
- In Band transmission
- RFC 2833 (RTP-NTE)
- Out of Band transmission
- KPML (RFC 4730)
- SIP Notify (RFC 3265)
- SIP Info (RFC 2976)
DTMF with MTP Involvement
- If MTP not checked on SIP trunk, User side is OOB
If MTP is required due to Asymmetric DTMF relay support, MTP will be invoked by CCM and OOB input will be injected to RTP by CCM via SCCP.
- If MTP is checked on SIP trunk, User side is OOB
MTP will be invoked by CCM and OOB input will be injected to RTP by CCM via SCCP.
- If MTP is checked on SIP trunk, both sides are RFC 2833
MTP will be invoked by CCM and RFC2833 pass-through is required on MTP
- If MTP is checked on SIP trunk, User Side is OOB and RFC 2833, SIP trunk side is RFC 2833
MTP will be invoked by CCM and OOB input will be injected to RTP by CCM via SCCP only when MTP does not support pass-through
Note: User side = phone registered to call manager placing an outbound call
SIP Trunk Early offer
Outbound Early Offer - MTP required checkbox needed for early offer before CUCM 8.5(1).
CUCM 8.5 supports early offer (without requiring MTP) when the call gets initiated from one of the following devices:
- SIP phones
- SCCP phones with SCCP v20 support (which provides media port information through the getPort capability)
- MGCP gateways
- Incoming H323 fast start calls
- Incoming early offer SIP trunk calls
Note: For the endpoints where the media port information is not available (e.g. H323 slow start calls or delayed offer SIP calls or legacy SCCP phones), Cisco Unified Communications Manager still allocates an MTP in order to provide SDP in the initial INVITE.
SIP Trunk DTMF Options
No Preference: CUCM will pick the DTMF method to negotiate DTMF, so an MTP is not required for the call. If Cisco Unified Communications Manager has no choice but to allocate an MTP (if the Media Termination Point Required check box is checked), SIP trunk will negotiate DTMF to RFC2833.
RFC 2833: CUCM makes every effort to negotiate RFC2833 regardless of MTP usage. Will fallback to OOB if needed.
OOB and RFC 2833: If both out of band and RFC2833 should be used for DTMF.
| RFC 2833 |
|---|
12/11/2011 09:53:17.399 CCM|//SIP/SIPUdp/wait_UdpDataInd: Incoming SIP UDP message size 1125 from 10.10.202.1:[58926]: INVITE sip:5002@10.10.210.10:5060 SIP/2.0 Via: SIP/2.0/UDP 10.10.202.1:5060;branch=z9hG4bK1825C Remote-Party-ID: <sip:3001@10.10.202.1>;party=calling;screen=no;privacy=off From: <sip:3001@10.10.202.1>;tag=5567AC-10F9 To: <sip:5002@10.10.210.10> Date: Sun, 11 Dec 2011 17:53:17 GMT Call-ID: D6FB694A-235711E1-8082DD38-3AA6E2D2@10.10.202.1 Supported: 100rel,timer,resource-priority,replaces,sdp-anat Min-SE: 1800 Cisco-Guid: 3600640543-592908769-2155732280-984015570 User-Agent: Cisco-SIPGateway/IOS-12.x Allow: INVITE, OPTIONS, BYE, CANCEL, ACK, PRACK, UPDATE, REFER, SUBSCRIBE, NOTIFY, INFO, REGISTER CSeq: 101 INVITE Max-Forwards: 70 Timestamp: 1323625997 Contact: <sip:3001@10.10.202.1:5060> Expires: 180 Allow-Events: telephone-event Content-Type: application/sdp Content-Disposition: session;handling=required Content-Length: 267 v=0 o=CiscoSystemsSIP-GW-UserAgent 914 6925 IN IP4 10.10.202.1 s=SIP Call c=IN IP4 10.10.202.1 t=0 0 m=audio 18010 RTP/AVP 0 101 19 c=IN IP4 10.10.202.1 a=rtpmap:0 PCMU/8000 a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-16 a=rtpmap:19 CN/8000 a=ptime:20 •Supports RFC2833 rtpmap: 101 a=rtpmap:<payload type> <encoding name>/<clock rate>[/<encoding parameters>] |
Key Press Markup Language (KPML)
- KPML procedures use a SIP SUBSCRIBE message to register for DTMF digits. The digits themselves are delivered in NOTIFY messages containing an XML encoded body.
- Out of Band DTMF
| KPML |
|---|
12/19/2011 11:28:56.437 CCM|//SIP/SIPUdp/wait_UdpDataInd: Incoming SIP UDP message size 852 from 14.48.20.15:[56433]: SUBSCRIBE sip:7071@14.48.46.2:5060 SIP/2.0 Via: SIP/2.0/UDP 14.48.20.15:5060;branch=z9hG4bK3B9BB From: <sip:2001@14.48.20.15>;tag=5B649D48-1331 To: <sip:7071@14.48.46.2>;tag=76443782-f2df-4954-81c7-811f18c00b73-25783280 Call-ID: 5FF97038-299511E1-8871E130-CC2C3FF8@14.48.20.15 CSeq: 102 SUBSCRIBE Max-Forwards: 70 Date: Mon, 19 Dec 2011 16:28:56 GMT User-Agent: Cisco-SIPGateway/IOS-12.x Event: kpml Expires: 7200 Contact: <sip:14.48.20.15:5060> Content-Type: application/kpml-request+xml Content-Length: 327 <?xml version="1.0" encoding="UTF-8"?><kpml-request xmlns="urn:ietf:params:xml:ns:kpml-request" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="urn:ietf:params:xml:ns:kpml-request kpml-request.xsd" version="1.0"><pattern persist="persist"><regex tag="dtmf">[x*#ABCD]</regex></pattern></kpml-request> 12/19/2011 11:28:56.439 CCM|//SIP/SIPUdp/wait_SdlSPISignal: Outgoing SIP UDP message to 14.48.20.15:[5060]: SIP/2.0 200 OK Date: Mon, 19 Dec 2011 16:28:56 GMT From: <sip:2001@14.48.20.15>;tag=5B649D48-1331 Content-Length: 0 To: <sip:7071@14.48.46.2>;tag=76443782-f2df-4954-81c7-811f18c00b73-25783280 Contact: <sip:14.48.46.2:5060> Expires: 7200 Call-ID: 5FF97038-299511E1-8871E130-CC2C3FF8@14.48.20.15 Via: SIP/2.0/UDP 14.48.20.15:5060;branch=z9hG4bK3B9BB CSeq: 102 SUBSCRIBE 12/19/2011 11:28:59.026 CCM|//SIP/SIPUdp/wait_UdpDataInd: Incoming SIP UDP message size 642 from 14.48.20.15:[56433]: NOTIFY sip:14.48.46.2:5060 SIP/2.0 Via: SIP/2.0/UDP 14.48.20.15:5060;branch=z9hG4bK3D25F0 From: <sip:2001@14.48.20.15>;tag=5B649D48-1331 To: <sip:7071@14.48.46.2>;tag=76443782-f2df-4954-81c7-811f18c00b73-25783280 Call-ID: 5FF97038-299511E1-8871E130-CC2C3FF8@14.48.20.15 CSeq: 104 NOTIFY Max-Forwards: 70 Date: Mon, 19 Dec 2011 16:28:59 GMT User-Agent: Cisco-SIPGateway/IOS-12.x Event: kpml Subscription-State: active Contact: <sip:14.48.20.15:5060> Content-Type: application/kpml-response+xml Content-Length: 113 <?xml version="1.0" encoding="UTF-8"?><kpml-response version="1.0" code="200" text="OK" digits="1" tag="dtmf"/> •Subscribe followed by 200 OK for the subscribe, then we will see NOTIFY messages with an XML body containing the digit pressed |
SIP Notify / Unsolicited Notify
Unsolicited Notify procedures are used to transport DTMF digits using SIP NOTIFY messages. Unlike KPML, these NOTIFY messages are unsolicited, and there is no prior registration to receive these messages using a SIP SUBSCRIBE message. But like KPML, Unsolicited Notify messages are out-of-band.
Also unlike KPML, which has an XML encoded body, the message body in these NOTIFY messages is a 10-character encoded digit, volume, and duration, describing the DTMF event.
| SIP Notify Advertisement |
|---|
12/15/2011 09:49:55.885 CCM|//SIP/SIPUdp/wait_UdpDataInd: Incoming SIP UDP message size 1190 from 14.48.20.15:[50042]: INVITE sip:7071@14.48.46.2:5060 SIP/2.0 Via: SIP/2.0/UDP 14.48.20.15:5060;branch=z9hG4bK212336 Remote-Party-ID: <sip:2001@14.48.20.15>;party=calling;screen=no;privacy=off From: <sip:2001@14.48.20.15>;tag=46709670-256F To: <sip:7071@14.48.46.2> Date: Thu, 15 Dec 2011 14:49:55 GMT Call-ID: E33AD68B-266211E1-885DE130-CC2C3FF8@14.48.20.15 Supported: 100rel,timer,resource-priority,replaces,sdp-anat Min-SE: 1800 Cisco-Guid: 3780284024-643961313-2287526192-3425452024 User-Agent: Cisco-SIPGateway/IOS-12.x Allow: INVITE, OPTIONS, BYE, CANCEL, ACK, PRACK, UPDATE, REFER, SUBSCRIBE, NOTIFY, INFO, REGISTER CSeq: 101 INVITE Max-Forwards: 70 Timestamp: 1323960595 Contact: <sip:2001@14.48.20.15:5060> Call-Info: <sip:14.48.20.15:5060>;method="NOTIFY;Event=telephone-event;Duration=2000" Expires: 180 Allow-Events: telephone-event Content-Type: application/sdp Content-Disposition: session;handling=required Content-Length: 245 |
SIP Notify Digit
To use SIP-Notify, the SIP Trunk Security Profile needs to accept unsolicited notification
| SIP Notify Digit |
|---|
12/15/2011 09:50:01.877 CCM|//SIP/SIPUdp/wait_UdpDataInd: Incoming SIP UDP message size 539 from 14.48.20.15:[50042]: NOTIFY sip:7071@14.48.46.2:5060 SIP/2.0 Via: SIP/2.0/UDP 14.48.20.15:5060;branch=z9hG4bK251965 From: <sip:2001@14.48.20.15>;tag=46709670-256F To: <sip:7071@14.48.46.2>;tag=76443782-f2df-4954-81c7-811f18c00b73-25783179 Call-ID: E33AD68B-266211E1-885DE130-CC2C3FF8@14.48.20.15 CSeq: 104 NOTIFY Max-Forwards: 70 Date: Thu, 15 Dec 2011 14:50:01 GMT User-Agent: Cisco-SIPGateway/IOS-12.x Event: telephone-event Subscription-State: active Contact: <sip:14.48.20.15:5060> Content-Type: audio/telephone-event Content-Length: 4 12/15/2011 09:50:01.879 CCM|getUnsolNotifyContents: Unsol NOTIFY message body is 0x040001f4, len=4 12/15/2011 09:50:01.879 CCM|getUnsolNotifyContents: getUnsolNotifyContents: Parsed digit=4, duration=500, end flag=0, duplicateEvent=0 |
SIP INFO
CUCM and IOS gateways can receive SIP INFO (RFC 2976) messages for DTMF but cannot generate them (CSCse50733)
| SIP INFO |
|---|
INFO sip:2143302100@172.17.2.33 SIP/2.0 Via: SIP/2.0/UDP 172.80.2.100:5060 From: <sip:9724401003@172.80.2.100>;tag=43 To: <sip:2143302100@172.17.2.33>;tag=9753.0207 Call-ID: 984072_15401962@172.80.2.100 CSeq: 25634 INFO Supported: 100rel Supported: timer Content-Length: 26 Content-Type: application/dtmf-relay Signal= 1 Duration= 160 |
Hope this is helpful. Thanks.
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