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Chapter 19

Australian P2 Protocol

19.1 Introduction

19.2 Signaling Overview

19.3 Parameters

: 19.3.1 Editable Parameters
: 19.3.2 Non-editable Parameters

19.4 Special TCP Behavior

: 19.4.1 Inbound Calls: Retrieving Digits All at Once
: 19.4.2 Inbound Calls: Retrieving Digits One at a Time

19.4.3 Outbound Calls: Digit Format

19.1 Introduction

This chapter provides the following information: · Overview of the signaling performed by the Australian P2 protocol · AP2 TCP parameters · Operations that are specific to the AP2 TCP within the framework of Natural Call Control.
The AP2 TCP implements the specifications of the Telstra CAS protocol P2. This protocol is widely used in Australia to connect PBXs to the PSTN, for Telstra and other carriers.

19.2 Signaling Overview

The Australian P2 protocol uses the line signaling scheme specified by the CCITT for the MFC-R2 protocol (Recommendation Q.421). Two bits are used for each direction. Thus the signaling channels supporting the line signaling of these protocols are referred to as Af and Bf in the forward direction, and Ab and Bb, in the backward direction. The forward channel indicates the condition of the outbound switch equipment and reflects the condition of the calling party's line. The backward channel indicates the condition of the called party's line (the inbound equipment). C and D bits are never used, and their value is fixed at 0 and 1 respectively.
The following table illustrates the signaling states of a typical call: State Outbound AfBf Direction Inbound AbBb Idle 10 \xdf 10 Seizure 00 01 Seizure Acknowledged 00 \xdf 11 Here the outbound side sends the address information. This is accomplished by in-band DTMF tones or decadic pulses. If decadic pulses are used, the Af bit pulses on and off to signal the address digits. If after all the address information has been transferred the inbound side accepts the call, it plays a ring tone on the line, and then signals that the call has been answered by setting the Ab bit to 0 Ringing 00 \xdf 11 Answer - conversation state 00 \xdf 01 If the inbound side rejects the call instead, the outbound side clears forward, by setting the Af bit to 1. The inbound side goes back to idle, by setting the Bb bit to 0 Clear forward 10 11 Idle 10 \xdf 10 During conversation the outbound protocol can receive billing pulses, to signal that a unit of cost has been billed to the call. The bit used to carry a billing pulse depends on national specifications. Answer - conversation state 00 \xdf 01 Billing pulses 00 \xdf 11 or 00 Answer - conversation state 00 \xdf 01 Depending on which of the sides hangs up the call first, we have a clear back signal, or a clear forward signal. Depending on national specifications, there might be a period of time in which the inbound side holds a release guard state, which is the same as clear back but happens when the outbound side is already in the idle state. Idle follows. Inbound hangs up first: Clear back 00 \xdf 11 Clear forward 10 11 Idle 10 \xdf 10 Outbound hangs up first: Clear forward 10 01 Release guard 10 \xdf 11 Idle 10 \xdf 10
The AP2 protocol uses either in-band DTMF tones or out-of-band decadic pulses to transfer register signaling information.
This protocols only transfers DID (direct inward dialing - the called address) information. To do this the outbound side sends either a stream of DTMF tones or a sequence of decadic pulses to the inbound side, then considers the dialing done and waits for some confirmation from the inbound side. This register signaling technique, in which the outbound side has no acknowledgment from the inbound side until the dialing is finished, is called "digit spill".

State	Outbound AfBf	Direction	Inbound AbBb
Idle	10	\xdf	10
Seizure	00		01
Seizure Acknowledged	00	\xdf	11
Here the outbound side sends the address information. This is accomplished by in-band DTMF tones or decadic pulses. If decadic pulses are used, the Af bit pulses on and off to signal the address digits. If after all the address information has been transferred the inbound side accepts the call, it plays a ring tone on the line, and then signals that the call has been answered by setting the Ab bit to 0
Ringing	00	\xdf	11
Answer - conversation state	00	\xdf	01
If the inbound side rejects the call instead, the outbound side clears forward, by setting the Af bit to 1. The inbound side goes back to idle, by setting the Bb bit to 0
Clear forward	10		11
Idle	10	\xdf	10
During conversation the outbound protocol can receive billing pulses, to signal that a unit of cost has been billed to the call. The bit used to carry a billing pulse depends on national specifications.
Answer - conversation state	00	\xdf	01
Billing pulses	00	\xdf	11 or 00
Answer - conversation state	00	\xdf	01
Depending on which of the sides hangs up the call first, we have a clear back signal, or a clear forward signal. Depending on national specifications, there might be a period of time in which the inbound side holds a release guard state, which is the same as clear back but happens when the outbound side is already in the idle state. Idle follows.
Inbound hangs up first: Clear back	00	\xdf	11
Clear forward	10		11
Idle	10	\xdf	10
Outbound hangs up first: Clear forward	10		01
Release guard	10	\xdf	11
Idle	10	\xdf	10

19.3 Parameters

The AP2 TCP is programmed by the parameters described below to implement the specifications of the supported countries and network operators. Caution: Most of the parameters that follow are signaling-specific: changing their value would not only invalidate any approval certificate for the used board, but would also most likely cause the board to malfunction. These parameters are described here for reference purposes only.
Other parameters program the interaction the TCP has with the host, or act on features not regulated or that can change from switch to switch within the same network. These are changeable, and indeed, the application developer is often asked to do so.

Caution:	Most of the parameters that follow are signaling-specific: changing their value would not only invalidate any approval certificate for the used board, but would also most likely cause the board to malfunction. These parameters are described here for reference purposes only.

19.3.1 Editable Parameters

Users can modify the following ADI.AP2 parameters: Field name Unit Default Description digitnumber number 7 Inbound: specifies number of incoming digits to expect optionflags number 0x1 · bit 0 and 1 (& 0x3): these two bits specify what to play as cleardown tone. This is the tone the TCP plays when an inbound call is released and the calling party hasn't hung up yet. The bits specify: - &0x1: play busy - &0x2: play reorder If none of the bits is set, the TCP remains silent. · bit 2 (& 0x4): if specified, the trunk is inbound only (outbound calls are not allowed) · bit 3 (&0x8): if specified, the trunk is outbound only (a seizure from the switch is treated as a fault) · bit 4 (&0x10): if specified, the TCP signals the network that the call is accepted when rejecting with user audio. With some protocols this is the only way to make a spoken reject message go through bit 5 (&0x20) specifying this bit forces the TCP to perform call progress, when all digits have been delivered to the network in an outbound call, even for protocols that give a positive indication of the state of the call. The default value is 0. This will not start call progress detection if the user sets the connect mask to connect on SIGNAL. This saves DSP resources. debugmask mask 0x0 Specifies generated trace messages are generated (run agtrace 1000 or higher to see them): · 0x01: Show all states as they are entered · 0x02: Show sent and received digits · 0x04: Show signaling bits · 0x08: Print a description of timeout- related errors These values can be ORed for cumulative effect.

Field name	Unit	Default	Description
`digitnumber`	`number`	`7`	Inbound: specifies number of incoming digits to expect
`optionflags`	`number`	`0x1`	· bit 0 and 1 (& 0x3): these two bits specify what to play as cleardown tone. This is the tone the TCP plays when an inbound call is released and the calling party hasn't hung up yet. The bits specify: - &0x1: play busy - &0x2: play reorder If none of the bits is set, the TCP remains silent. · bit 2 (& 0x4): if specified, the trunk is inbound only (outbound calls are not allowed) · bit 3 (&0x8): if specified, the trunk is outbound only (a seizure from the switch is treated as a fault) · bit 4 (&0x10): if specified, the TCP signals the network that the call is accepted when rejecting with user audio. With some protocols this is the only way to make a spoken reject message go through bit 5 (&0x20) specifying this bit forces the TCP to perform call progress, when all digits have been delivered to the network in an outbound call, even for protocols that give a positive indication of the state of the call. The default value is 0. This will not start call progress detection if the user sets the connect mask to connect on SIGNAL. This saves DSP resources.
`debugmask`	`mask`	`0x0`	Specifies generated trace messages are generated (run `agtrace` `1000 or higher to see them):` · `0x01: Show all states as they are entered` · `0x02: Show sent and received digits` · `0x04: Show signaling bits` · `0x08: Print a description of timeout- related errors` These values can be ORed for cumulative effect.

19.3.2 Non-editable Parameters

The following ADI.AP2 parameters are country or network-specific, and cannot be modified. Field Name Type/Unit Example Description seizureacktime ms 10000 Relevant to outbound protocols. Specifies time to wait for seizure acknowledgment after seizing the line. seizurewaittime ms 200 Relevant to outbound protocols. Specifies the time to wait to be seized in a two-way trunk, after the TCP seized the line. answerwaittime internal 90 Relevant to outbound protocols. Specifies the maximum time for the protocol to wait after the call accepted indication until the phone is answered (seconds). acceptwaittime ms 20000 Relevant to outbound protocols. Specifies the maximum time for the protocol to wait after dialing before being notified that either the call has been accepted and the phone is ringing, or that the call has been rejected. digitspilltime ms 20000 Relevant to inbound protocols. Specifies the total time the dialing process is allowed to take. waitforPCtime ms 20000 Relevant to inbound protocols. Specifies the time the protocol waits for the host to decide if an inbound call should be accepted or rejected. bitqualtime ms 20 Specifies the qualification time for bit changes. interdigitreceivetime ms 5000 Relevant to inbound protocols. While receiving decadic pulses, if the number of expected incoming digits is not known, this parameter specifies the time between two trains of pulses to conclude that the incoming dial string is finished. winktime ms 150 Relevant to inbound protocols. Specifies the duration of an inbound wink. Depending on the target country, the wink has a different meaning and occurs at different phases of call setup. toneontime ms 80 Specifies the time a DTMF tone should be ON while dialing. toneofftime ms 80 Specifies the time a DTMF tone should be OFF while dialing. pulseontime ms 50 Specifies the time a pulse should be ON while dialing with decadic pulses. pulseofftime ms 50 Specifies the time a pulse should be OFF while dialing with decadic pulses. hightoneamplitude IDU 352 Specifies the amplitude of the higher frequency of the DTMF tones while dialing. lowtoneamplitude IDU 440 Specifies the amplitude of the lower frequency of the DTMF tones while dialing. interdigitsendtime ms 700 Relevant to outbound protocols. Specifies the time between two trains of pulses while dialing with decadic pulses. ringfreq Hz 400 Relevant to inbound protocols. Specifies the ring tone frequency. ringontime ms 400 Relevant to inbound protocols. Specifies the time the ring tone is on in a ring cycle. ringofftime ms 200 Relevant to inbound protocols. Specifies the time the ring tone is off in a ring cycle. busyfreq Hz 425 Relevant to inbound protocols. Specifies the busy tone frequency. busyontime ms 375 Relevant to inbound protocols. Specifies the time the busy tone is on in a busy cycle. busyofftime ms 375 Relevant to inbound protocols. Specifies the time the busy tone is off in a busy cycle. fastbusyontime ms 375 Relevant to inbound protocols. Specifies the time the congestion tone is on. fastbusyofftime ms 375 Relevant to inbound protocols. Specifies the time the congestion tone is off. CPtoneslevel IDU 350 Relevant to inbound protocols. Specifies the amplitude of call progress tones (ring and busy). signalingflags mask 0x0 Two bytes devoted to the protocol's signaling flags. They are 0x1 DTMF (1) or decadic (0) dialing. AND the value of the parameter with this value to extract them. NMScountry internal 31 (Australia) NMS code for the target country. Timers related to the AG Quad board resource management resourcegettimes internal 0x0a0f This parameter addresses a special need of protocols running on a AG Quad board with resource management enabled. If this is the case, for certain operations it is necessary to acquire a resource from a resource pool on the board. The parameter defines to timeouts after which the operation is aborted if a resource is not available. This is a very unlikely occurrence though. · Low byte: time to wait for resource before placing a call (15 s) · High byte: time to wait for resource when a resource is needed by inbound to release a call (e.g. to play a cleardown tone) (10 s) Miscellaneous mintimeconnected time (ms) 250 inbound: the minimum time the TCP has to remain in the connected state (in order to allow the switch to bill the call) incomingqualtime time (ms) 65 inbound: signaling bits qualification time while playing ring tone (Italy only) releaseguardtime time (ms) 1000 inbound: minimum time the release guard signal must be on timewaitunblock time (ms) 0 time the TCP waits after receiving the command to unblock the line, before actually doing it and going to idle timeinterdigit time (ms) 400 inbound: minimum time between trains of decadic pulses maxbillingpulse time (ms) 200 outbound: maximum duration of billing pulse (for those protocols in which the line code of a billing pulse is the same as clear back) maxdecadicpulse time (ms) 100 inbound: maximum duration of decadic pulse (for those protocols in which the line code of a decadic pulse is the same as clear forward)

Field Name	Type/Unit	Example	Description
`seizureacktime`	`ms`	`10000`	Relevant to outbound protocols. Specifies time to wait for seizure acknowledgment after seizing the line.
`seizurewaittime`	`ms`	`200`	Relevant to outbound protocols. Specifies the time to wait to be seized in a two-way trunk, after the TCP seized the line.
`answerwaittime`	`internal`	`90`	Relevant to outbound protocols. Specifies the maximum time for the protocol to wait after the call accepted indication until the phone is answered (seconds).
`acceptwaittime`	`ms`	`20000`	Relevant to outbound protocols. Specifies the maximum time for the protocol to wait after dialing before being notified that either the call has been accepted and the phone is ringing, or that the call has been rejected.
`digitspilltime`	`ms`	`20000`	Relevant to inbound protocols. Specifies the total time the dialing process is allowed to take.
`waitforPCtime`	`ms`	`20000`	Relevant to inbound protocols. Specifies the time the protocol waits for the host to decide if an inbound call should be accepted or rejected.
`bitqualtime`	`ms`	`20`	Specifies the qualification time for bit changes.
`interdigitreceivetime`	`ms`	`5000`	Relevant to inbound protocols. While receiving decadic pulses, if the number of expected incoming digits is not known, this parameter specifies the time between two trains of pulses to conclude that the incoming dial string is finished.
`winktime`	`ms`	`150`	Relevant to inbound protocols. Specifies the duration of an inbound wink. Depending on the target country, the wink has a different meaning and occurs at different phases of call setup.
`toneontime`	`ms`	`80`	Specifies the time a DTMF tone should be ON while dialing.
`toneofftime`	`ms`	`80`	Specifies the time a DTMF tone should be OFF while dialing.
`pulseontime`	`ms`	`50`	Specifies the time a pulse should be ON while dialing with decadic pulses.
`pulseofftime`	`ms`	`50`	Specifies the time a pulse should be OFF while dialing with decadic pulses.
`hightoneamplitude`	`IDU`	`352`	Specifies the amplitude of the higher frequency of the DTMF tones while dialing.
`lowtoneamplitude`	`IDU`	`440`	Specifies the amplitude of the lower frequency of the DTMF tones while dialing.
`interdigitsendtime`	`ms`	`700`	Relevant to outbound protocols. Specifies the time between two trains of pulses while dialing with decadic pulses.
`ringfreq`	`Hz`	`400`	Relevant to inbound protocols. Specifies the ring tone frequency.
`ringontime`	`ms`	`400`	Relevant to inbound protocols. Specifies the time the ring tone is on in a ring cycle.
`ringofftime`	`ms`	`200`	Relevant to inbound protocols. Specifies the time the ring tone is off in a ring cycle.
`busyfreq`	`Hz`	`425`	Relevant to inbound protocols. Specifies the busy tone frequency.
`busyontime`	`ms`	`375`	Relevant to inbound protocols. Specifies the time the busy tone is on in a busy cycle.
`busyofftime`	`ms`	`375`	Relevant to inbound protocols. Specifies the time the busy tone is off in a busy cycle.
`fastbusyontime`	`ms`	`375`	Relevant to inbound protocols. Specifies the time the congestion tone is on.
`fastbusyofftime`	`ms`	`375`	Relevant to inbound protocols. Specifies the time the congestion tone is off.
`CPtoneslevel`	`IDU`	`350`	Relevant to inbound protocols. Specifies the amplitude of call progress tones (ring and busy).
`signalingflags`	`mask`	`0x0`	Two bytes devoted to the protocol's signaling flags. They are 0x1 DTMF (1) or decadic (0) dialing. AND the value of the parameter with this value to extract them.
`NMScountry`	`internal`	`31` `(Australia)`	NMS code for the target country.
Timers related to the AG Quad board resource management
`resourcegettimes`	`internal`	`0x0a0f`	This parameter addresses a special need of protocols running on a AG Quad board with resource management enabled. If this is the case, for certain operations it is necessary to acquire a resource from a resource pool on the board. The parameter defines to timeouts after which the operation is aborted if a resource is not available. This is a very unlikely occurrence though. · Low byte: time to wait for resource before placing a call (15 s) · High byte: time to wait for resource when a resource is needed by inbound to release a call (e.g. to play a cleardown tone) (10 s)
Miscellaneous
`mintimeconnected`	time (ms)	250	inbound: the minimum time the TCP has to remain in the connected state (in order to allow the switch to bill the call)
`incomingqualtime`	time (ms)	65	inbound: signaling bits qualification time while playing ring tone (Italy only)
releaseguardtime	time (ms)	1000	inbound: minimum time the release guard signal must be on
`timewaitunblock`	time (ms)	0	time the TCP waits after receiving the command to unblock the line, before actually doing it and going to idle
`timeinterdigit`	time (ms)	400	inbound: minimum time between trains of decadic pulses
`maxbillingpulse`	time (ms)	200	outbound: maximum duration of billing pulse (for those protocols in which the line code of a billing pulse is the same as clear back)
`maxdecadicpulse`	time (ms)	100	inbound: maximum duration of decadic pulse (for those protocols in which the line code of a decadic pulse is the same as clear forward)

19.4 Special TCP Behavior

The following sections describe operations that are specific to the AP2 TCP within the framework of Natural Call Control

19.4.1 Inbound Calls: Retrieving Digits All at Once

With the AP2 TCP, after ADIEVN_INCOMING_CALL is received, the calledaddr field in the ADI_CALL_STATUS structure contains all received digits. The callingaddr, usercategory and tollcategory fields are NULL.
The parameter ADI.AP2.digitnumber determines the number of digits the TCP should expect from the calling party. Default is 7.

19.4.2 Inbound Calls: Retrieving Digits One at a Time

The AP2 TCP does not recognize ANI or category digits. Digits are presented in the order in which they arrive. The ADI.AP2.digitnumber parameter determines how many digits to expect.

19.4.3 Outbound Calls: Digit Format

The AP2 TCP expects the digit string to be formatted as follows:
d1 dn
ANI and category indicators are not used in the AP2 TCP.

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