The many flavors of SIP

SIP over UDP is the accepted standard but there is also SIP over TCP and SIP over TLS (over TCP). Choosing a compatible solution is a key and often overlooked step in selecting a UC platform. According to the current spec, RFC 3261, "all SIP elements must implement UDP and TCP. SIP elements may implement other protocols." Let's dive a little deeper.

The Microsoft OCS team did a study on current UC market leaders and which protocols they support. To summarize they found that although SIP over UDP seems to be the accepted standard, every enterprise solution they examined also supports SIP over TCP and many support SIP over TLS. One platform they didn't include however is the open source Asterisk platform which oddly only supports SIP over UDP with SIP over TCP coming soon.

Here's a rundown of platforms and supported protocols

Microsoft

N

Y

Y

http://download.microsoft.com/download/d/b/6/db641148-427b-41d3-9f20-7ffbddaf65b8/OCS_VoIP_Guide.doc

Cisco

Y

Y

Y

http://www.cisco.com/en/US/docs/ios/12_4t/12_4t11/FeatTLS.html#wp1092137

IBM

N

Y

Y

http://download.boulder.ibm.com/ibmdl/pub/software/dw/lotus/sametime-sip.pdf

Nortel

Y

Y

Y

http://www142.nortelnetworks.com/techdocs/CS1K_5_0/pdf/NN43001-564_01.05_NRS.pdf

Avaya

Y

Y

Y

http://www.avaya.com/gcm/master-usa/en-us/products/offers/sip_enablement_services.htm&View=ProdTechSpec

Alcatel-Lucent

Y

Y

N

http://www1.alcatel-lucent.com/doctypes/articlepaperlibrary/pdf/ATR2002Q4/T0212-SIP_Technology-EN.pdf

Siemens

Y

Y

Y

http://www.enterprise-communications.siemens.com/Products/Phones%20Clients/Desktop%20Phones/~/media/6DAA007008EB4A5CA0212A6D12A49770.ashx

AudioCodes

Y

Y

Y

http://www.audiocodes.com/objects/sbc/nCite_4000.pdf

Nextpoint

Y

Y

Y

http://www.nextpointnetworks.com/files/NextPoint_SBC_USLTR_2008_hirez.pdf

Acme Packet

Y

Y

Y

http://www.acmepacket.com/html/page.asp?PageID={06E4AEBC-24E2-46CC-BA95-7C74288FA45B}

Covergence

Y

Y

Y

http://www.covergence.com/stuff/contentmgr/files/4adf40f79f81482fff714c46d8e06832/misc/ssesb.pdf

• Microsoft
• VoIP / Convergence
• OCS
• SIP