MGCP Call Flow – ISDN PRI

In a typical ISDN setup for an Inbound call from PSTN to an IP phone (-SCAC-)

CCM  –  GW  – PSTN

Setup <——-

Call proceeding ——->

Alerting ——->

Connect ——>

  1. Gateway and PSTN switch exchange Q921 Layer 2 information. Gateway registers with ISDN switch and terminates Q921 at gateway.
  2. A Q931 Setup message arrives. The gateway puts it in a packet and send it to CCM via TCP port 2428 (Backhaul)
  3. CCM then sends three Q.931 messages – Call proceeding, Alerting and connect
  4. After the call is brought up, CCM sends the gateway an MGCP MDCX to tell it parameters for connection
  5. Gateway sends an ack of connection
Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s