Outbound SIP Call with Call Agent Mode

With this feature, the CSP has the bearer on/off switching capability for outbound call legs too.

This capability is needed when the media services in the CSP (like DSP-2 card) or media transit path (like external TDM IVR or operator) is required for the called party.

Call Agent Mode (CAM) in the CSP provides dynamic switching of media streams on or off the CSP RTP channels with a minimal amount of SIP messages.

Prior to this feature, the CSP supported bearer on/off switching of Call Agent Mode for inbound calls only. The CSP can connect the inbound leg of a SIP call to a TDM network or to a DSP media service.

This functionality allows the caller to be connected to an operator in a PSTN network. It also allows the application of DSP services such as playing announcements to the calling (inbound) leg.

Bearer switching is based on a coupling and decoupling mechanism. Coupling associates a physical timeslot with a virtual timeslot to enable bearer-switched service. Decoupling dissociates a physical timeslot from a virtual timeslot to enable bearer-free switched service.

The bearer switching takes place whenever required with minimal interaction from the host.

With this feature, the CSP has the bearer on/off switching capability for outbound call legs too.

This capability is needed when the media services in the CSP (like DSP-2 card) or media transit path (like external TDM IVR or operator) is required for the called party.

Example: A directory assistance operator is located behind a TDM switch. The initial conversation between the operator and called party is bearer-switched through the CSP. Later, the operator drops out of the call flow while connecting the calling party and the called party bypassing the bearer path from the CSP.

The PPL Event Request (0x0024) is used to generate a
RE-INVITE message to the SIP endpoint connected to the channel indicated in the channel AIB.

This PPL Event Request will work only if the call is in bearer-free mode or else it will NACK with 0x130C (Call is not in bearer-free mode.)

The PPL Event Request is added to the SIP UA (0x00A7) component. When the PPL Event Request generates a RE-INVITE message, the 200 OK SIP message received from the other end having the SDP information will be reported to the host using the PPL Event Indication (0x0020) by the SIP UA component.

The data in the PPL Event Indication could be used within the subsequent Connect with Data (0x0005) message. The received PPL Event Request is ACKED if the data is valid.

The Outseize Control (0x002C) message is enhanced to support the following two TLVs within the Generic PPL ICB (0x001E):

ICB Type	0x03 (Extended Data)
ICB ID	0x001E
Data Length (2 bytes)	Variable
Number of TLVs (2bytes)	Variable
Tag	TLV 1 Tag
Length	TLV 1 Length
Value	TLV 1 Value
:	TLV n Tag
:	TLV n Length
:	TLV n Value
TLVs	0x0116 Channel Service 0x011A Call Agent Physical Channel ID

Value	Description	Corrective User Action
0x130C	Call not in bearer-free mode	Be sure call is in bearer-free mode.

The following messages are used by this feature. Refer to the API Reference for the formats.