Making a Call in the US using my UK Sim
 

I just put my 3UK Sim that I used last summer back into my phone. It is still active-- picked up T-Mobile. I gather that in order to keep it alive I need to make one call. I tried to do that but clearly didn't know the right combination of numbers to dial using my UK Sim in the US to dial a US number. I assumed it would be 001 + area code + plus 555-1111. Am I wrong?

Help!!!

Frankly, off the top of my head I don't know what the US [different from most of the world] outbound international code is. BUT '+' should always work anywhere in the world. Thus: +1xxxyyyqqqq should work for you.

Well, here is the info:
http://en.wikipedia.org/wiki/List_of..._call_prefixes

001 definitely not right. US is 011. 0011xxxyyyqqqq would be the way to do it. '+' is easier and if you use it when you create your phones address book the number would work anywhere in the world. 011 would be what you use with a land line.

Hi Lizzie,

The international call prefix in Europe is 00 while in the US it's 011 but the question is which dialing plan applies to your SIM card because today many operators have included a feature called "call completion" or "call correction" which allows subscribers using their domestic dialing plan abroad (e.g. offered by Starhome: http://www.starhome.com/call-completion.html). So even if you were supposed to dial 01144 from the US to the UK, the network could still connect you if you dialed 0044. Some networks are even configured to add the country code if you have forgotten it and if the dialed number doesn't exist in the visited country.
In any case, as rfranzq wrote, the best practice is to store all your numbers in the international format where + replaces the regional international prefix and you will never need to care about dialing plans again, regardless where you go to.

Here are some examples how numbers need to be entered correctly:
example for US number: 555 1234567 becomes +1 555 1234567
example for UK number: 02 12345678 becomes +44 2 12345678
example for German number: 030 12345678 becomes +49 30 12345678

Thanks, as always. I gather from the folks at Three that a Skype call would also keep the Sim alive. That was no problem.

I think I just make the 6 month deadline anyway. I left the UK on July 22 and will be returning on January 16....

It never hurts to test a week or so before you go to make sure it is still really working.

With UK SIM cards, usually any balance deduction is sufficient. While outside the UK, the cheapest balance deduction is probably an outgoing text or a brief incoming call (provided that incoming roaming calls are billed per second). I have a spare Three UK SIM card with zero credit on it, and in practice I keep it active with an incoming call (obviously free within the UK) every six months, for which Three receives a small amount of termination fees; however, this last method is not their official policy.