Q.931 is backhauled to CCM MANAGER ??

[Nitzbegin]

Can any one tell me what this line stands for and it means ??

I have got this one from my Voice Gateway ??

Im in a process of Learning the configuration of this device so got struck..

Nithin

[Adrian Saavedra]

Hello,

Backhaul means transporting signaling (all Q.931 messages) from an ISDN PRI/BRI interface on an MGCP gateway to CUCM for processing. That information is backhauled to CUCM through a TCP connection.

ISDN Q.931 is the L3 specification that is responsible for call control and management (call setup, tear down, etc).

Hope to help, please remember to rate the post if it does.

Kind regards,

- Adrian.

[Nitzbegin]

Hi Adrian,

1000 Thanks for your reply

I have studied somewhere that, MGCP is responsible for Communication between VG(MGCP) and Call Manager.

i.e As MGCP is a Call processing protocol thus it takes care of all these activities like (Call setup,Tear down etc)

for IP Phones.

Also please tell me how does Q.931 come in picture ?

What it actually does along with MGCP.?

Or

Is it something like Q.931 is only meant for Analog Phones communication with Call Manager ?

Awaiting 4 ur reply >

Nithin

[Adrian Saavedra]

Hi Nithin,

MGCP is a master-slave protocol, where the master is the call agent (e.g. CallManager) and the slave is the gateway. So, with MGCP, CallManager will centralize dial plan and control analog or digital voice ports on the gateway through a set of messages. The role of the MGCP gateway is media translation, it terminates the PSTN connections such as FXO, ISDN PRI, and receive instructions from CallManager to create connections when routing a call.

Q.931 is the L3 signaling protocol in ISDN for establishment and termination of calls. PRI/BRI circuits carry Q.921 and Q.931 signaling messages in the D-channel. The gateway terminates Q.921 but does not process Q.931 call control signals, instead, the gateway sends (e.g. backhaul) Q.931 messages (call setup, call proceeding, alerting, connect, release) to CallManager for processing.

The PRI call flow is:

1. The gateway and the PSTN exchange ISDN Q.921 L2 information. Q.921 information stops at the gateway.

2. Q.931 setup message arrives. The gateway sends it to CallManager using PRI backhaul. CallManager responds with MGCP message instructing the gateway to create a connection. The gateway acknowledge CallManager about the connection.

3. CallManager then sends Q.931 messages (call proceeding, alerting, connect) through the gateway to PSTN.

4. After the call is up, CallManager sends the gateway an MGCP message to tell the parameters for the connection.

5. CallManager gets an acknowledge of the connection from the other side and then sends a message to the gateway in order to have a two way communication.

Hope to help, please remember to rate the posts if it does!.

Kind regards,

- Adrian.

[Nitzbegin]

Adrian ,

This is really helpful for me....

[Adrian Saavedra]

Nithin,

Glad to see it helps, and thank you!

Regards,

Adrian.

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