Budget Hotel in Mumbai 4am

We're arriving in Mumbai at 4am and thinking of staying at the Volga II cause it's was recommended on LP. I'd like to book ahead, but I'm not sure I have a full phone number, does this look like enough to call from the UK + country code? 2824755

Or any other recommendations for a budget hotel up to around 500 Rs that I can prebook by email or phone and not give our my credit card number to?

Will they keep a room for us a room that early/late?

That phone number is too short. India phone numbers are 8 digits preceded by the city code (which for Mumbai is 22). So calling from the UK, it's country code 091, then 22, then the 8 digit number.

Add a "2" to your 7 digit local number to get the requisite 8 digits. So....

+91 22 22824755