Refer : System – > Cisco Callmanager Page
Ethernet Phone Port – Default is 2000. We changed to 4000. Phones started using TCP port 4000.
Digital Port – Default is 2001. This is used by DT-24+ cards
Analog Port – Default is 2002 . This is used by 6624-FXS card for Catalyst 6509.
MGCP Listen port – Default is 2427. This can be changed to any port.Make sure to configure the same port in the MGCP gateway ( router config).
MGCP keep-alive port – Default is 2428.
All these ports can be configured from the range 1024 – 49151.