Validate Mobile number using regular expression

Question

I need to validate mobile number. My need:

1. The number may start with +8801 or 8801 or 01
2. The next number can be 1 or 5 or 6 or 7 or

Answer 1

Bangladeshi phone number (Citycell, Robi, Grameen Phone, Banglalink, Airtel and Teletalk operators) validation by using regular expression :

$pattern = '/(^(\+8801|8801|01|008801))[1-9]{1}(\d){8}$/';
$BangladeshiPhoneNo = "+8801840001417";

if(preg_match($pattern, $BangladeshiPhoneNo)){
    echo "It is a valid Bangladeshi phone number;
}