formatting local mobile to international in php - php

Question

I am looking for a simple regex to convert both UK (44) and Indian (91) numbers into a valid international format using PHP. The formats required are:
447856555333 (for uk mobile numbers)
919876543456 (for indian mobile numbers)
I need a regex that will accept and format the following variations:
1) 07856555333
2) 0785 6555333
3) 0785 655 5333
4) 0785-655-5333
5) 00447856555333
6) 0044785 6555333
7) 0044785 655 5333
8) 0044785-655-5333
9) 00447856555333
10) [phone]
11) [phone]
12) [phone]
13) [phone]
14) [phone]
15) 00919876543456
Any help would be much appreciated.
UPDATE: Based on answer below I have amended the code slightly and it works very well. It is not bullet proof but covers most of the popular formats:
public static function formatMobile($mobile) {
$locale = '44'; //need to update this
$sms_country_codes = Config::get('sms_country_codes');
//lose any non numeric characters
$numeric_p_number = preg_replace("#[^0-9]+#", "", $mobile);
//remove leading zeros
$numeric_p_number = preg_replace("#^[0]*#", "", $numeric_p_number);
//get first 2 digits
$f2digit = substr($numeric_p_number, 0,2);
if(strlen($numeric_p_number) == 12) {
if(in_array($f2digit, $sms_country_codes) ) {
//no looks ok
}
else {
return ""; //is correct length but missing country code so must be invalid!
}
}
else {
if(strlen($locale . $numeric_p_number) == 12 && !(in_array($f2digit, $sms_country_codes))) {
$numeric_p_number = $locale . $numeric_p_number;
//the number is ok after adding the country prefix
} else {
//something is missing from here
return "";
}
}
return $numeric_p_number;
}

Answer 1

for your particular scope think something like this might work ... not really a regex-only solution but should do the trick for your needs:
$locale = "your_locale_prefix";
$valid_codes = array("44","91");
//loose any non numeric characters
$numeric_p_number = preg_replace("#[^0-9]+#", "", $phone_number);
//remove leading zeros
$numeric_p_number = preg_replace("#^[0]*#", "", $numeric_p_number);
//get first 2 digits
$f2digit = substr($numeric_p_number, 0,2);
if(in_array($f2digit, $valid_codes) && strlen($numeric_p_number) == 12){
//code is ok
} else {
if(strlen($locale . $numeric_p_number) == 12) {
//the number is ok after adding the country prefix
} else {
//something is missing from here
}
}