PRACKMethod

    
 

Description

The PRACK message plays the same role as ACK, but instead provides acknowledgment for provisional responses. This allows provisional responses to be exchanged reliably.

Guidelines

You may select one of the following three settings:

Disabled

This means that we cannot do PRACK.

  • When we initiate a call, our Invite will not have any header with the 100rel tag in it. If the far end sends a reliable provisional, we will not respond with a PRACK.

  • When we receive an Invite containing a Require header with a 100rel tag, we will send a 420 response having an Unsupported header with a 100rel tag.

  • When we receive an Invite containing a Supported header with a 100rel tag or no 100rel tag, we will send normal, non-reliable provisionals.

Supported (default)

This means that PRACK is in passive mode.  

  • When we initiate a call, our Invite will have a Supported header with the 100rel tag.  If the far end sends a provisional with the RSeq header, we will be able to respond properly.

  • When we receive an Invite containing a Supported or Required header with 100rel, we will send reliable provisionals.

  • When we receive an Invite containing no 100rel at all, we will NOT send reliable provisionals.

Required

This means that PRACK is in active mode.

  • When we initiate a call, our Invite will have a Require header with the 100rel tag. If the far end responds with a 420 response and an Unsupported header with 100rel, the call will fail.

  • When we receive an Invite with the 100rel tag in either the Supported or Require header, we will send reliable provisionals.

  • When we receive an Invite without a 100rel tag, then we will fail the call with a "403 Forbidden" response.

Related Topics

SIPSignalingGroup-1 (sipsg 1) Prompt Commands

Configuration Manager

Location

VoIP Configuration > SIP Signaling Groups > SIP Signaling Group-n > Advanced tab > PRACK Method

Options

Select from the drop-down box. Valid options are as follows:

  • Disabled

  • Supported

  • Required

Command Line

Cmd Type

Command

Prompt Level

config-SIPSignalingGroup-1#

Syntax

set prackmethod or prackm { 0 | 1 | 2 }

Arguments

0   Disabled

1   Supported

2   Required

Default

1   Supported

Examples

config-SIPSignalingGroup-1# set prackm 2

Sets the Tenor to require PRACK messaging.