Information Technology Reference
In-Depth Information
The CUCM performs digit analysis on the dialed digits, and finds a match for phone#2 (not shown in
Figure 3-1).
The CUCM now sends information about the calling party to phone#2, such as calling party name, calling party number, and so on.
The CUCM also indicates to phone#2 that it should blink its lamp and that it should ring.
The CUCM then sends an alerting (ringback) message to phone#1.
The user of phone#2 answers the phone, and an off-hook message is sent to the CUCM.
The CUCM responds by telling phone#2 to stop blinking its lamp (set it to a steady state) and to stop the ring tone.
The CUCM also informs phone#1 to end the ringback tone.
Next, the CUCM requests information regarding the Real-time Transport Protocol (RTP) (for example, the IP address to/from which
RTP should be sent/received). Both phones respond, and the CUCM then informs each phone of the other's RTP information.
RTP traffic now flows between the phones, and the users begin their conversation.
The user of phone#1 now ends the call, and phone#1 sends an on-hook message to the CUCM.
The CUCM notifies the phones to close the media channel and end media transmission. It also informs the phones to set their lamp
states to off.
Finally, phone#2 sends an on-hook message to the CUCM.
SCCP can signal numerous call states, including the following:
1: Off Hook
2: On Hook
3: Ring Out
4: Ring In
5: Connected
