CASr1 scripting

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Revision as of 09:39, 30 July 2013

E&M is a CASr1 family. This script is used to configure the following variants:

Immediate delay
Wink-start
Double-ack

Summary

This script will be identified as a CASR1 script when the following variable is set:

SCRIPT_TYPE="CASR1"

The CASR1 script allows implementation of all variants of CASR1 stacks by controlling what actions must take place following received events.

Overview

The script will received an indication for each timeslot it has to "control" through function HandleNewTimeslot. The script will then be notified of any event on that timeslot (CAS bits changes and others). To each received event, the script will take one ore more action.

It's up to the script implementation to define it's own states for handling the calls. The script is thus very flexible in the way it implements the CASR1 variant call flow.

The current document does not describe how CASR1 call flows are implemented (what are CAS bits, when and why to they "change", how calling/called numbers are exchanged, what is the call flow etc.) The reader shall find that information in the specifications for CASR1 variants. This script should provide all tools required to actually implement CASR1 variants.

Configurable global script constants

The script can define some constants required by the stack (though default values are provided if the script does not define these constants.

SCRIPT_TYPE 				= "CASR1"

Defines the type of this sript. Must be CASR1 in current case.

ABCD_PATTERN_MATCH_MASK 	= 0x1111

Mask to apply to CAS bits detected from remote equipment. A bit which mask is set to 0 will be ignored and always reported as zero (0) to this script. This is useful in some cases when unused bits have undefined (and even sometimes toggeling!) values.

TONE_USE_DTMF			 	= 1

Indicates the type of tones must be used to send/receive AND/DNIS. Value of 1 stands for DTMF. Value of 0 defaults to MFR1.

	DTMF mapping:
		'0'	->	DTMF Digit 0: 				941Hz + 1336Hz
		'1'	->	DTMF Digit 1: 				697Hz + 1209Hz
		'2'	->	DTMF Digit 2: 				697Hz + 1336Hz
		'3'	->	DTMF Digit 3: 				697Hz + 1477Hz
		'4'	->	DTMF Digit 4: 				770Hz + 1209Hz
		'5'	->	DTMF Digit 5: 				770Hz + 1336Hz
		'6'	->	DTMF Digit 6: 				770Hz + 1477Hz
		'7'	->	DTMF Digit 7: 				852Hz + 1209Hz
		'8'	->	DTMF Digit 8: 				852Hz + 1336Hz
		'9'	->	DTMF Digit 9: 				852Hz + 1477Hz
		'*'	->	DTMF Digit Star (*): 		941Hz + 1209Hz
		'#'	->	DTMF Digit Pound (#): 		941Hz + 1477Hz
		'A'	->	DTMF Digit A: 				697Hz + 1633Hz
		'B'	->	DTMF Digit B: 				770Hz + 1633Hz
		'C'	->	DTMF Digit C: 				852Hz + 1633Hz
		'D'	->	DTMF Digit D: 				941Hz + 1633Hz
		Alternative values for * and #:
		'E'	->	DTMF Digit Star (*): 		941Hz + 1209Hz
		'F'	->	DTMF Digit Pound (#): 		941Hz + 1477Hz

MFR1 mapping:

		'0'	->	MFR1 Digit 0: 				1300Hz + 1500Hz
		'1'	->	MFR1 Digit 1: 				700Hz  + 900Hz
		'2'	->	MFR1 Digit 2: 				700Hz  + 1100Hz
		'3'	->	MFR1 Digit 3: 				900Hz  + 1100Hz
		'4'	->	MFR1 Digit 4: 				700Hz  + 1300Hz
		'5'	->	MFR1 Digit 5: 				900Hz  + 1300Hz
		'6'	->	MFR1 Digit 6: 				1100Hz + 1300Hz
		'7'	->	MFR1 Digit 7: 				700Hz  + 1500Hz
		'8'	->	MFR1 Digit 8: 				900Hz  + 1500Hz
		'9'	->	MFR1 Digit 9: 				1100Hz + 1500Hz
		'*'	->	MFR1 KP (Start of pulsing):	1100Hz + 1700Hz
		'#'	->	MFR1 ST (End of pulsing):	1500Hz + 1700Hz
		'A'	->	MFR1 STI: 					900Hz  + 1700Hz
		'B'	->	MFR1 STII: 					1300Hz + 1700Hz
		'C'	->	MFR1 STIII: 				700Hz  + 1700Hz
		'D'	->	Not supported in MFR1

Alternative characters:

		'E'	->	MFR1 KP (Start of pulsing):	1100Hz + 1700Hz
		'F'	->	MFR1 ST (End of pulsing):	1500Hz + 1700Hz

TONE_ON_TIME				= 60

Determines the "on time" (in ms) of tones used when sending ANI/DNIS.

TONE_OFF_TIME				= 50

Determines the "off time" (inter-digit delay)(in ms) of tones used when sending ANI/DNIS.

TONE_LEVEL				= -10

Determines the level (in DB) of tones used when sending ANI/DNIS.

Static constants pushed by the stack, for usage in this script

Available actions for "StackAction" function: Commonly used actions:

		ACTION_END_SIGNALING
		ACTION_SET_CAS_BITS
		ACTION_SEND_WINK
		ACTION_WAIT_WINK
		ACTION_SEND_ANI
		ACTION_SEND_DNIS
		ACTION_WAIT_ANI
		ACTION_WAIT_DNIS
		ACTION_REPORT_SEIZURE
		ACTION_REPORT_VALIDATE_CALL
		ACTION_REPORT_ACCEPTED
		ACTION_REPORT_ALERTED
		ACTION_REPORT_ANSWERED
		ACTION_REPORT_BLOCKED
		ACTION_REPORT_UNBLOCKED
		ACTION_START_TIMER
		ACTION_CANCEL_TIMER

Additional actions to implement special variants

		ACTION_SEND_TONE
		ACTION_SET_ANI
		ACTION_SET_DNIS

Events received by this script on "HandleEvents" function: Commonly used events:

		EVENT_CAS_BITS_CHANGED
		EVENT_WINK_DETECTED
		EVENT_WINK_COMPLETED
		EVENT_ANI_RECEIVED
		EVENT_DNIS_RECEIVED
		EVENT_ANI_SENT
		EVENT_DNIS_SENT
		EVENT_APP_FWD_MAKE_CALL
		EVENT_APP_BWD_MUST_ALERT
		EVENT_APP_BWD_MUST_ANSWER
		EVENT_APP_END_SIGNALING
		EVENT_APP_BLOCK_TIMESLOT
		EVENT_APP_UNBLOCK_TIMESLOT
		EVENT_TIMEOUT

Additional events to implement special variants EVENT_TONE_RECEIVED EVENT_TONE_SENT

Result code that HandleNewTimeslot or HandleEvent funtions must return:

	RESULT_OK
	RESULT_FAIL
	RESULT_MISMATCH
	RESULT_OUT_OF_RESOURCE
	RESULT_INVALID_PARAM
	RESULT_INVALID_STATE
	RESULT_NOT_SUPPORTED
	RESULT_TRUNK_RES_NOT_IDLE
	RESULT_BLOCKED_LOCALLY
	RESULT_BLOCKED_REMOTELY

Call release causes to use with ACTION_END_SIGNALING

	CAUSE_FWD_SEIZURE_COLLISION
	CAUSE_FWD_SEIZURE_ACK_TIMEOUT
	CAUSE_FWD_TONE_TIMEOUT
	CAUSE_FWD_ANSWER_TIMEOUT
	CAUSE_FWD_CALL_REFUSED
	CAUSE_FWD_REJECT_CALL
	CAUSE_FWD_HANG_UP
	CAUSE_BWD_TONE_TIMEOUT
	CAUSE_BWD_REJECT_CALL
	CAUSE_BWD_CALL_REFUSED
	CAUSE_BWD_ALERT_TIMEOUT
	CAUSE_BWD_ANSWER_TIMEOUT
	CAUSE_BWD_HANG_UP

Trace levels (used with function StackLogTrace). Least verbose is TRACE_LEVEL_0 (almost never printed). Most verbose is TRACE_LEVEL_4 (generally printed)

	TRACE_LEVEL_0
	TRACE_LEVEL_1
	TRACE_LEVEL_2
	TRACE_LEVEL_3
	TRACE_LEVEL_4
	TRACE_LEVEL_ALWAYS
	TRACE_LEVEL_ERROR

Mandatory functions to implement in this script

The script must provide the following mandatory functions, that will be called by the CAS stack at appropriate moments.

HandleNewTimeslot( in_TimeslotCtx, in_InitialCasBits )

This function is called to prepare a new timeslot so it's ready to be used to receive events and eventually handle a CASR1 call. When this function is called, the timeslot must be set to "off-hook" state. The stack will later send EVENT_APP_UNBLOCK_TIMESLOT when it's time to go "on-hook" and be ready to make calls.

Parameters:

in_TimeslotCtx :

Context containing variables for this timeslot. This context is a LUA table. This table already contains two values: ["TrunkNumber"] and ["TimeslotNumber"] The script can create it's own variables here (like the "call state"), which will be accessible for any event on this timeslot.

in_InitialCasBits :

The initial states of CAS bits received from remote equipment (integer like 0x1111)

HandleEvent( in_TimeslotCtx, in_EventType, ... )

This function reports that an event occurred on a timeslot

Parameters :

in_TimeslotCtx :

Timeslot context used by the script to store any timeslot- related information, like the "call state". This is the table that was passed to HandleNewTimeslot.

in_EventType :

The type of the event that was just received (see constants EVENT_* documented below)

... :

Variable number of parameters, that depend on event type. Available event types and their parameters:

EVENT_CAS_BITS_CHANGED

Parameter:

- Received CAS bits (integer like 0x1111) Indicates that CAS bits values received by remote equipment have changed.

EVENT_WINK_DETECTED

No specific parameter.

Indicates that a "Wink" has been detected. This event can only follow ACTION_WAIT_WINK.

EVENT_WINK_COMPLETED

No specific parameter.

Indicates that a "Wink" has been sent successfully. This event can only follow ACTION_SEND_WINK.

EVENT_TONE_RECEIVED

Parameter:

- String that represents the received tone (digit) (see "Digit format" below) Indicates that a tone was detected. Not normally used in CASR1 standard variants.

Note: This does not include tones that are collected as part of ACTION_WAIT_ANI or ACTION_WAIT_DNIS, which are coalesced and reported as separate events.

EVENT_ANI_RECEIVED

No specific parameter.

Indicates that ANI (calling number) has been sent received (prefix/suffix detected). This event can only follow ACTION_WAIT_ANI. Note: The received ANI/DNIS digits are not passed to the script. The script does not have to know them. But the stack keeps them and they will be reported to the application upon ACTION_REPORT_VALIDATE_CALL

EVENT_DNIS_RECEIVED

Same as EVENT_ANI_RECEIVED, but for DNIS (called number)

EVENT_TONE_SENT

No specific parameter.

Indicates that a tone (digit) as been sent successfully following ACTION_SEND_TONE. Not normally used in CASR1 standard variants.

EVENT_ANI_SENT

No specific parameter.

Indicates that ANI (calling number) has been sent successfully (all tones played). This event can only follow ACTION_SEND_ANI.

EVENT_DNIS_SENT

Same as EVENT_ANI_SENT, but for DNIS (called number)

EVENT_APP_FWD_MAKE_CALL

No specific parameter.

Indicate that a new "forward" call must be made. The script shall take appropraite actions to initiate a new call (most likely change the CAS bits to the "off hook" state).

EVENT_APP_BWD_MUST_ALERT

No specific parameter.

Indicates that this "backward" call must now be set to "alerted" state (meaning we have accepted the call, and received required information to proceed). The decision of when to alert the call is made by the application, and at that moment the script receives this event so it can take appropriate actions to alert a "backward" call. (in most variants, there is nothing to do, on some variants, a "Wink" may be sent).

EVENT_APP_BWD_MUST_ANSWER

No specific parameter.

Indicates that this "backward" call must now be set to "answered" state. The decision of when set the call "answered" is made by the application, and at that moment the script receives this event so it can take appropriate actions to answer. (in most variants, CAS bits must be set to an "answered" pattern).

EVENT_APP_END_SIGNALING

No specific parameter.

Indicates either that: - Application requests to terminate the call. The script then take appropriate action, like sedding CAS bits to "idle" state, wait for remote equipment to acknowledge, then at the end use ACTION_END_SIGNALING to confirm that termination is completed. - Script previously called ACTION_END_SIGNALING, (after remote equipment set CAS bits to "idle" or after an error in the script), in which case this event confirms that the application is also ready to terminate the call.

EVENT_APP_BLOCK_TIMESLOT

No specific parameter.

Indicates that the timeslot must be locally blocked, the next time it becomes "idle". It's blocked by going "off-hook" and remaining in that state no matter remote state. This is also the default state for a newly created timeslot. This state can only be canceled by EVENT_APP_UNBLOCK_TIMESLOT

EVENT_APP_UNBLOCK_TIMESLOT

No specific parameter.

Cancels a previous EVENT_APP_BLOCK_TIMESLOT. This causes our CAS bits to be set to "on hook".

EVENT_TIMEOUT
<pre>
					No specific parameter.

					Indicates that the timer previously started with
					ACTION_START_TIMER has expired.
	Returns : 
		RESULT_OK, or one of the return codes defined above.
		This result code tells to the stack if the event was properly
		handled by the script. Upon non-OK code, the stack may decide
		to terminate the call.

== Stack functions that can be called by this script ==	

=== StackActionToString( in_Action ) ===
	Returns string value of an action type.
	Example:
		local action = ACTION_END_SIGNALING
		StackActionToString( action )
		will return the string "ACTION_END_SIGNALING".
	

=== StackEventToString( in_Event ) ===
	Returns string value of an event type.
	Example:
		StackEventToString( in_Event )
		will return the string "EVENT_TIMEOUT".


=== StackCauseToString( in_Cause ) ===
	Returns string value of a release cause.
	Example:
		my_release_cause = CAUSE_FWD_SEIZURE_COLLISION
		StackCauseToString( my_release_cause )
		will return the string "CAUSE_FWD_SEIZURE_COLLISION".

=== StackLogTrace( in_TraceLevel, in_Format, ... ) ===
	Asks the stack to print a trace (generally debug traces).
	Traces will be sent to the "tblogtrace" application.
	Parameters:
		'''in_TraceLevel''':
			Level of the trace (see TRACE_LEVEL_* above)
		'''in_Format''':
			String that contains the trace to print, plus refernences
			to other arguments ("printf" style format)
		..'''.''':
			Values for printf-style refernces of in_Format.
	Example:
		local cas_bits = 0x1100
		StackLogTrace( TRACE_LEVEL_2, "Send CAS bits %08X", cas_bits )
		will print "Send CAS bits 1100" to tblogtrace log.
		

=== StackAction( in_Action, ... ) ===
	This function executes the specified action (in some cases with
	the specified action-specific arguments).
	The action is done asynchronously, meaning that control will 
	immediately return to the script. Events will be received later
	according to the actions taken.
	Upon an event, the script may perform multiple actions (like
	starting a timer, declarign the call "alerted" and sending
	CAS bits for example)
	Parameters : 
		'''in_Action''' :
			The action to perform.
			(see constants ACTION_* documented below)
		'''...''' :
			Variable number of action-specific arguments.
				ACTION_END_SIGNALING:
					Parameter:
						- The call release cause to report.
						  See values "CAUSE_".
					Indicates either that:
					  - Application previously requested to terminate
					    the call (with EVENT_APP_END_SIGNALING), in
						which case this action is used by the script
						to indicate that signaling is fully idle (local
						CAS bits set to "idle", remote equipment 
						has acknowledged too with "idle" CAS bits).
					  - Script wants to terminate the call
					    (after remote equipment set CAS bits to "idle"
						or after an error in the script). After
						sending ACTION_END_SIGNALING, the script must
						wait until EVENT_APP_END_SIGNALING is
						received, which confirms that application is
						ready to terminate the cally. Only at that
						moment the script shall set it's CAS bits
						to "idle" value.
				ACTION_SET_CAS_BITS
					Parameter:
						- CAS bits to set (integer like 0x1111)
					Used to change the CAS bits that we are
					sending on current timeslot towawrd remote
					equipment.
				ACTION_SEND_WINK
					Parameters:
						- 	CAS bits to set during the "Wink"
							(integer like 0x1111)
						- 	Duration of the "Wink" (in milliseconds)
					Used to send a "Wink", which is temporary change of
					the CAS bits for few milliseconds, then back to
					initial CAS bits value.
					EVENT_WINK_COMPLETED will be received by
					the script once Wink has completed (CAS bits are
					back to their initial value)
				ACTION_WAIT_WINK
					Parameters:
						- 	Expected CAS bits during the "Wink"
							(integer like 0x1111)
						- 	Minimum duration of the "Wink" (in ms)
						- 	Maximum duration of the "Wink" (in ms)
					Used to request a "Wink" detection.
					Upon next CAS bits change from remote equipment,
					the stack will see if the bits match the Wink
					expected bits.
					EVENT_WINK_DETECTED will be reported
					if CAS bits received from remote equipment change
					to the expected pattern for a duration within
					specified range, then go back to original value.
					Any other CAS bits change not deteced as a "Wink"
					will be reported to the script by
					EVENT_CAS_BITS_CHANGED (which will probably want
					to drop the call because a Wink was expected)
				ACTION_SEND_TONE
					Parameters:
						- 	Digit (tone) to send.
							(see "Digit format" below)
					Used to send one digit (tone) toward remote
					equipment. EVENT_TONE_SENT will be received
					once the tone has been successfully sent.
					Not normally used in CASR1 standard variants.
					Note:	This action is not used to send ANI/DNIS
							(calling/called numbers), it's used to
							send other tones that may be used within
							the current CASR1 variant call flow.
				ACTION_SEND_ANI
					Parameters:
						- 	Prefix to send before ANI. Can be empty.
						- 	Suffix to send after ANI. Can be empty.
							(see "Digit format" below)
					Used to send ANI (calling number) toward
					remote equipment, using tones.
					A prefix may be inserted before ANI.
					A suffix is mandatory. It's transmitted after ANI.
					Remote equipment expects that suffix to determine
					that the ANI has been entirely sent.
					EVENT_ANI_SENT will be received once 
					transmission of prefix + ANI + suffix completed
				ACTION_SEND_DNIS
					Same as ACTION_SEND_ANI, but for sending DNIS
					(called number)
				ACTION_WAIT_ANI
					Parameters:
						- 	Prefix to expect before ANI. Can be empty.
						- 	Suffix to expect after ANI. Can be empty only
							if next argument (nb expected digits) is set.
							(see "Digit format" below)
						- 	Number of expected digits.
							Optional. Only required if suffix is empty.
					Used to wait for ANI (calling number) from
					remote equipment, by detecting tones.
					A prefix may be expected before ANI.
					A suffix is mandatory. It's received after ANI to
					indicate that the ANI has been entirely transmitted.
					EVENT_ANI_RECEIVED will be received if a
					matching prefix + suffix are detected.
				ACTION_WAIT_DNIS
					Same as ACTION_WAIT_ANI, but for receiving DNIS
					(called number)
				ACTION_SET_ANI
					Parameters:
						- 	ANI to set
					Used to replace the ANI detected by the stack with
					this ANI provided by the script.
					This action must be calld before action
					TBX_CASR2VMLIB_CASR1_ACTION_REPORT_VALIDATE_CALL
					(otherwise it's too late to set ANI)
					Not normally used in CASR1 standard variants.
				ACTION_SET_DNIS
					Same as ACTION_SET_ANI, but for DNIS (called number)
				ACTION_REPORT_SEIZURE
					No parameter.
					Tell the application that seizure (off-hook) has
					been deteced on a timeslot.
				ACTION_REPORT_VALIDATE_CALL
					No parameter.
					Tell the application that ANI and/or DNIS have
					been successfully received, and we now have the
					information required to process this incoming call.
				ACTION_REPORT_ACCEPTED
					No parameter.
					Tell the application that a "forward" call has
					been accepted by remote equipment, often by
					detecting a "Wink".
				ACTION_REPORT_ALERTED
					No parameter.
					Tell the application that a "forward" call has
					been alerted by remote equipment.
					On most variants, there is no specific indication
					from remote side, and this action must be taken
					upon EVENT_DNIS_SENT.
					On other variants, a "Wink" may be awaited before
					calling this action.
				ACTION_REPORT_ANSWERED
					No parameter.
					Tell the application that a "forward" call has
					been answered by remote equipment, generally
					because "off-hook" CAS bits have been received.
				ACTION_REPORT_BLOCKED
					No parameter.
					Tells the application that the script considers
					the timeslot as "remotely blocked". This is the
					case when remote side goes "off hook" and remains
					in that state for some duration after we've
					returned to "on hook" on our side.
				ACTION_REPORT_UNBLOCKED
					NO parameter.
					Tells the application that the timeslot is no
					more "remotely blocked", because remote
					equipment went "on hook" after we reported
					ACTION_REPORT_BLOCKED.
				ACTION_START_TIMER
					Parameter:
						- Timer duration in milliseconds.
					Starts a timer. EVENT_TIMEOUT will be
					posted if the timer expires before
					ACTION_CANCEL_TIMER is called.
				ACTION_CANCEL_TIMER
					No parameter.
					Cancels a timer previously started with
					ACTION_START_TIMER.
			
	Digit format:
		The digit format (for sending tone or ANI/DNIS prefix/suffix)
		is represented by a string that contains up to 3 of the
		following characters: 0123456789ABCD*#

CASr1 scripting

Revision as of 09:39, 30 July 2013

Contents

Summary

Overview

Configurable global script constants

Static constants pushed by the stack, for usage in this script

Mandatory functions to implement in this script

HandleNewTimeslot( in_TimeslotCtx, in_InitialCasBits )

HandleEvent( in_TimeslotCtx, in_EventType, ... )

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@@ Line 249: / Line 249: @@
 === HandleEvent( in_TimeslotCtx, in_EventType, ... ) ===
 	This function reports that an event occurred on a timeslot
 	Parameters :
 		'''in_TimeslotCtx''' :
 			Timeslot context used by the script to store any timeslot-
 			related information, like the "call state".
 			This is the table that was passed to HandleNewTimeslot.
 		'''in_EventType''' :
 			The type of the event that was just received
 			(see constants EVENT_* documented below)
 		'''...'''	:
 			Variable number of parameters, that depend on event type.
 			Available event types and their parameters:
-				EVENT_CAS_BITS_CHANGED:
+<pre>
+EVENT_CAS_BITS_CHANGED
+</pre>
 					Parameter:
 						- Received CAS bits (integer like 0x1111)
 					Indicates that CAS bits values received by
 					remote equipment have changed.
-				EVENT_WINK_DETECTED:
+<pre>
-					No specific parameter.
+EVENT_WINK_DETECTED
+</pre>
+No specific parameter.
 					Indicates that a "Wink" has been detected.
 					This event can only follow ACTION_WAIT_WINK.
-				EVENT_WINK_COMPLETED:
+<pre>
-					No specific parameter.
+EVENT_WINK_COMPLETED
+</pre>
+No specific parameter.
 					Indicates that a "Wink" has been sent successfully.
 					This event can only follow ACTION_SEND_WINK.
-				EVENT_TONE_RECEIVED
+<pre>
+EVENT_TONE_RECEIVED
+</pre>
 					Parameter:
 						- 	String that represents the received tone (digit)
 							(see "Digit format" below)
 					Indicates that a tone was detected.
 					Not normally used in CASR1 standard variants.
-					Note:	This does not include tones that are
+'''Note''':	This does not include tones that are
 							collected as part of ACTION_WAIT_ANI or
 							ACTION_WAIT_DNIS, which are coalesced and
 							reported as separate events.
-				EVENT_ANI_RECEIVED
+<pre>
-					No specific parameter.
+EVENT_ANI_RECEIVED
+</pre>
+No specific parameter.
 					Indicates that ANI (calling number) has been
 					sent received (prefix/suffix detected).
@@ Line 293: / Line 316: @@
 							and they will be reported to the
 							application upon ACTION_REPORT_VALIDATE_CALL
-				EVENT_DNIS_RECEIVED
+<pre>
+EVENT_DNIS_RECEIVED
+</pre>
 					Same as EVENT_ANI_RECEIVED, but for DNIS
 					(called number)
-				EVENT_TONE_SENT
+<pre>
-					No specific parameter.
+EVENT_TONE_SENT
+</pre>
+No specific parameter.
 					Indicates that a tone (digit) as been sent
 					successfully following ACTION_SEND_TONE.
 					Not normally used in CASR1 standard variants.
-				EVENT_ANI_SENT
+<pre>
-					No specific parameter.
+EVENT_ANI_SENT
+</pre>
+No specific parameter.
 					Indicates that ANI (calling number) has been
 					sent successfully (all tones played).
 					This event can only follow ACTION_SEND_ANI.
-				EVENT_DNIS_SENT
+<pre>
+EVENT_DNIS_SENT
+</pre>
 					Same as EVENT_ANI_SENT, but for DNIS
 					(called number)
-				EVENT_APP_FWD_MAKE_CALL
+<pre>
+EVENT_APP_FWD_MAKE_CALL
+</pre>
 					No specific parameter.
 					Indicate that a new "forward" call must be made.
 					The script shall take appropraite actions to
 					initiate a new call (most likely change the
 					CAS bits to the "off hook" state).
-				EVENT_APP_BWD_MUST_ALERT
+<pre>
+EVENT_APP_BWD_MUST_ALERT
+</pre>
 					No specific parameter.
 					Indicates that this "backward" call must now
 					be set to "alerted" state (meaning we have accepted
@@ Line 326: / Line 365: @@
 					(in most variants, there is nothing to do, on
 					 some variants, a "Wink" may be sent).
-				EVENT_APP_BWD_MUST_ANSWER
+<pre>
+EVENT_APP_BWD_MUST_ANSWER
+</pre>
 					No specific parameter.
 					Indicates that this "backward" call must now
 					be set to "answered" state. The decision of when
@@ Line 335: / Line 377: @@
 					(in most variants, CAS bits must be set to
 					 an "answered" pattern).
-				EVENT_APP_END_SIGNALING
+<pre>
+EVENT_APP_END_SIGNALING
+</pre>
 					No specific parameter.
 					Indicates either that:
 					  - Application requests to terminate the call.
@@ Line 349: / Line 394: @@
 						case this event confirms that the application
 						is also ready to terminate the call.
-				EVENT_APP_BLOCK_TIMESLOT
+<pre>
+EVENT_APP_BLOCK_TIMESLOT
+</pre>
 					No specific parameter.
 					Indicates that the timeslot must be locally
 					blocked, the next time it becomes "idle".
@@ Line 359: / Line 407: @@
 					This state can only be canceled by
 					EVENT_APP_UNBLOCK_TIMESLOT
-				EVENT_APP_UNBLOCK_TIMESLOT
+<pre>
+EVENT_APP_UNBLOCK_TIMESLOT
+</pre>
 					No specific parameter.
 					Cancels a previous EVENT_APP_BLOCK_TIMESLOT.
 					This causes our CAS bits to be set to "on hook".
-				EVENT_TIMEOUT
+<pre>
+EVENT_TIMEOUT
+<pre>
 					No specific parameter.
 					Indicates that the timer previously started with
 					ACTION_START_TIMER has expired.