Session Initiation Protocol
Cisco Unified Call Manager version 5.0 and later support SIP line side support which allows any third-party SIP based phone to register with Call Manager (rebranded as Cisco Unified Communications Manager around the 6.0 time frame). The third party phone integration in Call Manager is compliant with the IETF RFC3261 (SIP version 2.0). Third party phones can will be able to make phone calls, put calls on hold, transfer, and conference calls; but will lack Cisco Call Manager features that are not a part of the RFC3261 standard. This blog will explain the different support Call Manager has for SIP based endpoints. A Cisco 7900 series phone runs the skinny client control protocol (SCCP) by default, but all of Cisco’s 7900 series phones support session initiation protocol (SIP). Cisco’s phones are commonly referred to as Type A and Type B to identify the generation of the Cisco phone’s hardware (ASIC, DSP, DRAM, flash, etc.). The generation of phone is very important to know to identify the feature set that will be supported on that particular phone if they are converted to SIP. Cisco’s Type A phones will lose many of the features that Call Manager provides when the phone is running a SCCP binary image load. I recommendation that you do not convert Cisco Type A phones to SIP if you are running Call Manager or Call Manager Express due to the number of missing features. Cisco Type B phones have near feature parity to Cisco Type B phone in Cisco Unified Communications Manager (CUCM) 7.0 and above. Call Manager 5.0 and above provides over 90% of the Call Manger feature set to SIP based Cisco phones, but the SIP support was increased in CUCM 7.0. Third party SIP phones can be purchased from vendors like Linksys, Avaya, Nortel, Siemens, etc. X-Lite is a software based phone that is free to download and use. Registering the X-Lite phone will require either a basic or advanced SIP third party device. Basic configuration will provide only one line, while the advanced version supports up to eight lines. The basic configuration will cost 3 device license units (DLU) in Call Manager, while the advanced configuration will require 6 available DLUs. The X-Lite client can support up to 3 lines. Additional information on CUCM licensing is in the references section of this blog. The next blog will continue our SIP conversation. In the next blog, we will take a look at the third party phone integration configuration for Cisco Unified Communications Manager. REFERENCES X-Lite Phone Download http://www.counterpath.com/x-lite.html&active=4 CUCM Licensing http://www.cisco.com/en/US/prod/collateral/voicesw/ps6788/vcallcon/ps556/ps6164/prod_qas0900aecd805009fc_ps556_Products_Q_and_A_Item.html Licensing Chapter of Call Manager SRND: http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/7_1_2/ccmsys/a02licen.pdf
