I think there is no additional requirement needed to run SIP phone with your call manager version6.1 instead your network should have the following requirements:
⢠Working Voice-over-IP (VoIP) Network
- VoIP configured on your Cisco routers and gateways
- Cisco Unified Communications Manager Release 3.3(5) or higher installed in your network and configured to handle call processing
The minimum firmware release that must be installed on the phone is 7.2(1).
IP network that supports DHCP or manual assignment of IP address, gateway, and subnet mask