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Impact in rel1xx disable command

Peterson Cristovam
Participant
Participant

Hi guys

In an environment with

UCM 8.6 ----> SBC (internal) -----> SBC (Servce Provider) -----> destination

What is the impact of this command:

rel1xx disable

and

rel1xx enable

Can you help me with clarification?

1 ACCEPTED SOLUTION

Accepted Solutions

This command is used to require reliability of provisional responses. Provisional responses are 180 ringing, 183 session progress hence the reason for 1XX.. PRACK is used for this purpose

By default provisional responses are not sent reliably. Hence if a 183 session progress is sent and lost, it will not be retransmitted.

When you enable relxx, you are telling the other party that you want reliability with your provisional responses...consequently when you disable it, you return back to the default behaviour which is to send provisional responses unreliably.

In some scenarios PRACK is used when the end party wants to play annoucnement or some media before sending a 200 OK, in scenarios like this you will need to enable rel1xx

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"opportunity is a haughty goddess who waste no time with those who are unprepared"

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View solution in original post

3 REPLIES 3

This command is used to require reliability of provisional responses. Provisional responses are 180 ringing, 183 session progress hence the reason for 1XX.. PRACK is used for this purpose

By default provisional responses are not sent reliably. Hence if a 183 session progress is sent and lost, it will not be retransmitted.

When you enable relxx, you are telling the other party that you want reliability with your provisional responses...consequently when you disable it, you return back to the default behaviour which is to send provisional responses unreliably.

In some scenarios PRACK is used when the end party wants to play annoucnement or some media before sending a 200 OK, in scenarios like this you will need to enable rel1xx

Please rate all useful posts

"opportunity is a haughty goddess who waste no time with those who are unprepared"

Please rate all useful posts

Hello Ayodeji,

 

If the other end is sending 180/183 messages with 100rel required.

How can we enable on our device to send PRACK messages?

We can configured voice gateway on a router and we are facing issues in the outgoing calls.

When I have checked in the logs we are getting 180/183 messages with 100rel require. So I want to know do we have to enable PRACK messages on router or these are by default enabled.

 

 

Regards,
MUKESH KUMAR | Network Engineer
Spooster IT Services
Computer Networking Solutions

Hi Mukesh,

If you are using SIP trunk between CUCM and Voice Gateway for out bound try to configure your SIP profile as "Send PRACK if 1xx contains SDP". You can find this info in SIP Profile settings you are using with in Trunk.

Check the scree shot for further idea.

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