Cisco takes a bitter sip of SIP in call manager 5.0

Cisco Systems has announced plans to adopt a key Internet Protocol telephony standard, which will allow for the addition of new network service features and will let companies like Microsoft integrate their communications products with Cisco gear.
Cisco is one of the last telephony vendor to accept SIP, it does kind of seem that Cisco was dragged kicking and screaming into the SIP camp. May be it got scared of all the IP-PBX systems that over taking Cisco with their products. Specially open source solutions like Asterisk, SipX and OpenSer.