Call Progress Notification to Host with PPL Event Indication


When the host application initiates an outbound SIP call using the Route Control or Outseize Control message, the CSP can receive one or more provisional responses from the remote endpoint before receiving the 200 OK message.

Pertinent Specification

RFC 2543/3261

API Messages

Route Control (0x00E8)

Outseize Control (0x002C)

PPL Event Indication (0x0043)


Use the PPL Event Notification Mask (0x0282) TLV in the VoIP Configure message to configure the PPL events that you want the host application to see.

Refer to the Tag Length Value Blocks chapter in the API Reference.

Refer to the180 Ringing PPL Event Indication 0x0024 for the PPL Information: SIP UA 0x00A7.

Call Flow

If the call flow has both 180 and 183 responses, the CSP sends the host application the PPL Event Indication for 180 Ringing (0x0024) and PPL Event Indication for 183 Ringing (0x001F) as indicated below.