CUCM Architecture: IP Phone Communication and Call Flow

Key Protocols

  • Skinny (SCCP) (Signaling)
  • SIP (Signaling)
  • RTP (Audio)

Phones sends off hook status to CUCM.

All actions for the handset are actioned by the CUCM brain.

Call setup via CUCM and audio stream directly between the 2 phones via RTP. (CODECs to follow)

SCCP does digit by digit processing.

SIP almost sends a micro version of the dial plan to the phone!