Hi Seifeddine,

Hope all is well with you :)

CME support for SIP was first introduced in CME 3.4 and has evolved through CME 4.1 but is only supported on Cisco Phone models. Have a look at the following;

CME 3.4

http://www.cisco.com/en/US/products/sw/voicesw/ps4625/prod_installation_guide09186a008055677f.html

Cisco Unified SIP IP Phone 7905G and Cisco Unified SIP IP Phone 7912 for Cisco CallManager Express 3.4

http://www.cisco.com/univercd/cc/td/doc/product/voice/its/cme34/cme34rc1.htm

Cisco Unified SIP IP Phone 7960G and Cisco Unified SIP IP Phone 7940G for Cisco CallManager Express 3.4

http://www.cisco.com/univercd/cc/td/doc/product/voice/its/cme34/cme34rc2.htm

CME 4.1

SIP Features for Cisco Unified CME 4.1,

http://www.cisco.com/univercd/cc/td/doc/product/voice/its/cme41/cme410ft.htm

How to Configure SIP Features for Cisco Unified CME 4.1

http://www.cisco.com/univercd/cc/td/doc/product/voice/its/cme41/cme410ft.htm#wp1049437

Hope this helps!

Rob

Here is the official line on Third Party Endpoints (shown for the Cisco Smart Business Communication System but of course based on CME) ;

Q. Can I use third-party SIP phones?

A. The Cisco Smart Business Communication System is capable of working with third-party phones; however third-party phones have not yet gone through proper testing for official support.

Cisco Smart Business Communication System

http://www.cisco.com/en/US/products/ps7293/products_qanda_item0900aecd806a7b2d.shtml

Hope this helps!

Rob