mobiles

[tedja]

what does the +44 mean when you are asked for your mobile number

[Mobius1]

It is the UK's dialling identity code. When calling from abroad to the UK, the normal area code requires a prefix number. For instance, if the UK number was 01579 445897 then from abroad it'd be 44-1759 44897. Usually you drop the zero and add the country code.

Mobiles and particularly text messages often display this. It just means that the message has been specifically sent to a UK mobile. If I'm not mistaken anyway.

[badams]

44 is the international dialing code for the UK.  The + sign replaces the International Direct Dialing code which indicates to the telephone system that the following digits are an international dialing code. In the UK, the IDD code is 00, so for example, to dial Ireland from the UK, you would dial 00353 followed by the Irish telephone number, without its leading zero.  If you replace all of the numbers in your mobile with the international dialing codes, you can roam freely without having to edit the numbers in your phone depending on the country you are in.

+44 literally means "this is an international dialing code - it is for the UK".  The telephone system is smart enough to know that when you dial the +44 prefix in the UK, it does not need to route it through an international call centre.