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*                                                                                                 *
* a2billing 1.x (c) AGPL 2003-2010                                                                *
* Documentation                                                                                   *
*                                                                                                 * 
* Title: Callback                                                                                 *
* Date: April 2009                                                                                *
* Version: 1.0                                                                                    *
* Author: AB                                                                                      *
* Status: Draft                                                                                   *
*                                                                                                 *
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CALLBACK

	The Document Explains you following topics
	1. Introduction
	2. Basic description of the Callback
	3. Table CallBack
	4. CallBack Solution
		4.1 Web Callback
		4.2 ANI Callback
		4.3 DID Callback
		4.4 API Callback.



1. INTRODUCTION
	
	Astersik2Billing provides an extensive functionality to handle the Callback.
	It supply solutions for Web Callback, ANI Callback, DID Callback, API Callback.



2. BASIC DESCRIPTION OF THE CALLBACK

	Description of the Callback in 10 steps :
	
		1. The client makes a phone call to one of our access numbers. His Caller ID 
		information must be available from his phone carrier (not blocked).
		
		2. The server sees the incoming call and processes it with the appropriate context 
		(ex. cid-callback)
		
		3. The custom_calling_card context will call the AGI provided with 
		A2Billing (a2billing.php) and uses it in cid-callback mode. 
		
		4. The AGI will check the detected Caller ID and check if it’s an existing client. 
		If that is the case, it will schedule a callback for that client and it will hang up 
		the line.
		
		5. A few seconds later, the server calls the client and use an another context that 
		will let A2Billing know that this is the 2nd phase of a callback process.
		
		6. A2Billing will use the number called to lookup various account specific information
		(account balance, currency settings, and so on).
		
		7. As soon as the client picks up the line, A2Billing will play his remaining balance,
	 	and invite him to dial a number
		
		8. The client dials a number
		
		9. A2Billing will tell the maximum time for the call and so on.
		
		10. ...
		
		
		
3. TABLE CALLBACK_SPOOL

	
	id			Id of the table
	uniqueid 	 	Unique ID to cross-check with other platform 
	entry_time		Time the record is stored in this table
	status 	 		enum('NEW', 'QUEUE', 'SENT', 'UPDATED', 'DEAD')	
	server_ip 	 	Server IP receive the callback to initiate and handle
	
	num_attempt		number of attempt
	last_attempt_time	Time the record is stored in this table
	manager_result		Originate
	agi_result		Ok, Hangup, etc...
	
	callback_time		Time to start to initiate the callback
	
	channel			Channel on which to originate the call (SIP/123@1.1.1.4)
	exten			Extension to use on connect (must use Context & Priority with it)
	context			Context to use on connect (must use Exten & Priority with it)
	priority		Priority to use on connect (must use Context & Exten with it)
	application		Application to use on connect : meetme or other 
				(use Data for parameters)
	data			Data if Application parameter is used
	timeout			Timeout for the connection to happen (30000)
	callerid		CallerID to use for the call
	variable		Callback info for Asterisk
				(variable list to transfer to the channel) 
				var1=23|var2=24|var3=25 
	account			Account code for the call for billing purpose
	async			For the origination to be asynchronous (allows multiple calls to be 
				generated without waiting for a response)
	actionid		The request identifier. It allows you to identify the response to this
				request. You may use a number or a string. 
				Useful when you make several simultaneous requests. 
				ActionID: ABC45678901234


4. Issue with remove international prefix

	Remove international prefix doesnt work on call-back, the callerID is used to outbound and also to authenticate the call,
	so if you get 0034XXX, you have to :
	Either parse the callerID before callback context and remove the 00 (any international prefix) in front of the CallerID
	or set the rates inside the ratecard with the international prefix, like 0034, 0044