Simple PHP script that checks the extension status at a remote PBX and updates a custom hint on the local pbx for proper BLF operation.

## remotehintpoll.php
<?php

/**** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** ****
 * remotehintpoll.php
 *
 * Created by Lorne Gaetz lgaetz@sangoma.com
 *
 * Latest version: https://gist.github.com/lgaetz/8545099
 *
 * Licensed under GNU GPL version 2 or any later verison.
 *
 * Usage:
 * This script is intended to be used on a local FreePBX system running version 2.9 or higher. When
 * executed, the script polls a remote Asterisk server using remote Asterisk Manager Interface
 * (AMI) credentials, checks the status of a specific extension number on the remote server, and
 * then updates a local hint to the same value.
 *
 * Asterisk configuration:
 * Define a dynamic hint on the local system of the same  format as what is dialled to reach an
 * extension on the remote system. If remote extensions are of the format 10XX and you use a dial
 * prefix of 55 to dial remote extensions, the local dynamic hint is defined in extensions_custom.conf as:
 *
 *			[from-internal-custom]
 *			exten => _5510XX,hint,Custom:Remote${EXTEN:2}   // program BLF with e.g. 551001
 *
 * If you don't dial a prefix to reach the remote extensions from the local pbx, the hint looks like:
 *
 * 			[from-internal-custom]
 *			exten => _10XX,hint,Custom:Remote${EXTEN}      // program BLF with e.g. 1001
 *
 * Version history:
 *			2014-01-21  Initial commit for single extension
 *			2017-06-22  Add support to poll a range of extensions and update a local dynamic hint
 *
 **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** **** ****/

// set to true to echo debug
$debug=true;

// Set the local device prefix for the local hint, must match what is defined in extensions_custom.conf for the hint
// the $device_prefix will be used to prefix the remote extension number for the hint
$device_prefix = "Custom:Remote";

// Remote server host/IP, AMI credentials and
$remote_server = "hostname_placeholder";
$remote_name = "name";
$remote_secret = "password";
$remote_context = "from-internal";

// define range or remote extension numbers to poll, the fewer the better
// the range needs to match the dynamic hint noted above
$remote_extension_start='1000';
$remote_extension_end='1010';

// Connect to local machine with FreePBX bootstrap, requires FreePBX 2.9 or higher
if (!@include_once(getenv('FREEPBX_CONF') ? getenv('FREEPBX_CONF') : '/etc/freepbx.conf')) {
	include_once('/etc/asterisk/freepbx.conf');
}

// connect to remote Asterisk machine using AMI credentials and get status of Extension 103
$remote = new AGI_AsteriskManager();
if ($remote->connect($remote_server, $remote_name, $remote_secret)) {
	for ($remote_extension=$remote_extension_start; $remote_extension<=$remote_extension_end; $remote_extension++) {
		$foo[$remote_extension] = $remote->ExtensionState($remote_extension, $remote_context);
	}
	$remote->disconnect();
}
else {
	output("Can not connect to remote AGI");
}

// print_r($foo);  //for debug

// Based on value of remote extension status, change local custom device state to match
// edit $device to reflect name of local custom device as defined in extensions_custom.conf
// in the [from-internal-custom] section add a line similar to:
// exten => 103,hint,Custom:Remote103
// Make sure that the number does not conflict with something else

if($astman->connected()) {
	for ($remote_extension=$remote_extension_start; $remote_extension<=$remote_extension_end; $remote_extension++) {
		switch ($foo[$remote_extension]['Status']) {
			case -1:
				output("$remote_extension Extension not found");
				$cmd = $astman->Command('devstate change '.$device_prefix.$remote_extension.' UNKNOWN');
				break;
			case 0:
				output("$remote_extension Idle");
				$cmd = $astman->Command('devstate change '.$device_prefix.$remote_extension.' NOT_INUSE');
				break;
			case 1:
				output("$remote_extension In Use");
				$cmd = $astman->Command('devstate change '.$device_prefix.$remote_extension.' INUSE');
				break;
			case 2:
				output("$remote_extension Busy");
				$cmd = $astman->Command('devstate change '.$device_prefix.$remote_extension.' BUSY');
				break;
			case 4:
				output("$remote_extension Unavailable");
				$cmd = $astman->Command('devstate change '.$device_prefix.$remote_extension.' UNAVAILABLE');
				break;
			case 8:
				output("$remote_extension Ringing");
				$cmd = $astman->Command('devstate change '.$device_prefix.$remote_extension.' RINGING');
				break;
			case 9:
				output("$remote_extension Ringing");
				$cmd = $astman->Command('devstate change '.$device_prefix.$remote_extension.' RINGING');
				break;
			case 16:
				output("$remote_extension On Hold");
				$cmd = $astman->Command('devstate change '.$device_prefix.$remote_extension.' ONHOLD');
				break;
			default:
			   output("$remote_extension Extension not found");
			   $cmd = $astman->Command('devstate change '.$device_prefix.$remote_extension.' UNKNOWN');
		}
	}
} else {
    output("Can not connect to local AGI");
}

function output($string){
	global $debug;
	if ($debug) {
		echo $string."\n";
	}
}