Posted by: Mudassir Ali | January 9, 2012

A Comparison of SIP and H.323 Trunks

A Comparison of SIP and H.323 Trunks

Cisco Unified CM trunk connections support both SIP and H.323. In many cases, the decision to use SIP or H.323 is driven by the unique feature(s) offered by each protocol. There are also a number of external factors that can affect the choice of trunk protocol, such as customer preference or the protocol’s maturity and degree of interoperability offered between various vendors’ products.

For trunk connections between Cisco devices, this decision is relatively straightforward. For trunk connections to other vendors’ products and to service provider networks, it is important to understand which features are required by the customer and the extent of interoperability between any two vendors’ products.

Table compares some of the features offered over SIP and H.323 trunks between Cisco Unified CM clusters.

Table Comparison of SIP and H.323 Features on Cisco Unified Communications Manager Trunks
Feature SIP QSIG over SIP H.323 QSIG over H.323
Calling Line (Number) Identification Presentation Yes Yes Yes Yes
Calling Line (Number) Identification Restriction Yes Yes Yes Yes
Calling Name Identification Presentation Yes Yes Yes Yes
Calling Name Identification Restriction Yes Yes Yes Yes
Connected Line (Number) Identification Presentation Yes Yes Yes Yes
Connected Line (Number) Identification Restriction Yes Yes Yes Yes
Connected Name Identification Presentation Yes Yes Yes Yes
Connected Name Identification Restriction Yes Yes Yes Yes
Alerting Name Yes Yes No Yes
Call Transfer (Blind/Attended) Yes/Yes Yes/Yes Yes/Yes Yes/Yes
Call Forward All Yes Yes Yes Yes
Call Forward Busy Yes Yes Yes Yes
Call Forward No Reply Yes Yes Yes Yes
Call Completion to Busy Subscriber No Yes No Yes
Call Completion No Reply No Yes No Yes
Subscribe/Notify, Publish – Presence Yes Yes No No
Message Waiting Indication (MWI: lamp ON, lamp OFF) Yes Yes No Yes
Path Replacement No Yes No Yes
Call Hold/Resume Yes Yes Yes Yes
Music On Hold (unicast and multicast) Yes Yes Yes Yes
DTMF-relay RFC 2833, KPML (OOB), Unsolicited Notify (OOB) RFC 2833, KPML (OOB), Unsolicited Notify (OOB) H.245 Out Of Band (OOB)1 H.245 Out Of Band (OOB)1
SIP Early Offer Yes – MTP may be required Yes – MTP may be required N/A N/A
SIP Delayed Offer Yes Yes N/A N/A
H.323 Fast Start N/A N/A Yes – MTP always required for Outbound Fast Start Yes – MTP always required for Outbound Fast Start
H.323 Slow Start N/A N/A Yes Yes
Audio codecs G.711, G.722, G.723, G.729, iLBC, AAC, iSAC G.711, G.722, G.723, G.729, iLBC, AAC, iSAC G.711, G.722, G.723, G.729 G.711, G.722, G.723, G.729
Codecs with MTP All codecs supported when Early Offer support for voice and video calls (insert MTP if needed) is checked

G.711, G.729 when MTP Required is checked

All codecs supported when Early Offer support for voice and video calls (insert MTP if needed) is checked

G.711, G.729 when MTP Required is checked

G.711, G.723, G.729 G.711, G.723, G.729
Video Yes Yes Yes Yes
Video codecs H.261, H.263, H.263+, H.264 AVC H.261, H.263, H.263+, H.264 AVC H.261, H.263, H.263+, H.264 AVC H.261, H.263, H.263+, H.264 AVC
T.38 Fax Yes Yes Yes Yes
Signaling Authentication Digest, TLS Digest, TLS No No
Signaling Encryption TLS TSL No No
Media Encryption (audio) SRTP SRTP SRTP SRTP
RSVP-based QoS and call admission control Yes Yes No No
Support for + character Yes Yes No No
Inbound Calls — Called Party: Significant Digits, Prefix-Digits Yes Yes Yes Yes
Incoming Calling Party Settings: Strip Digits, Prefix-Digits based on Number Type SIP does not support Number Type – "Unknown" used for all calls SIP does not support Number Type – "Unknown" used for all calls Cisco Unified CM, Unknown, National, International, Subscriber Cisco Unified CM, Unknown, National, International, Subscriber
Incoming Called Party Settings: Strip Digits, Prefix-Digits based on Number Type N/A N/A Cisco Unified CM, Unknown, National, International, Subscriber Cisco Unified CM, Unknown, National, International, Subscriber
Connected Party Transformation Yes Yes No No
Outbound Calling Party Transformations Yes Yes Yes Yes
Outbound Called Party Transformations Yes Yes Yes Yes
Outbound Calling/Called Party Number Type Setting SIP does not support Number Type SIP does not support Number Type Cisco Unified CM, Unknown, National, International, Subscriber Cisco Unified CM, Unknown, National, International, Subscriber
Outbound Called/Called Party Numbering Plan Setting SIP does not support Number Plan SIP does not support Number Plan Cisco Unified CM, ISDN, National Standard, Private, Unknown Cisco Unified CM, ISDN, National Standard, Private, Unknown
Trunk destination — State detection mechanism OPTIONS Ping OPTIONS Ping Per call attempt Per call attempt

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/8x/trunks.html

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