- 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!