Can you change your mobile network and still keep your number?

I want to change from T-Mobile to Three, but on three use a micro sim for my new iPhone. However, will they let me keep my number? Oh, and on T-Mobile I'm pay as you go but on Three I will pay monthly.

Yes! Ask your network provider for a PAC code and when they give you it phone up your new network and give them the code. Will take a few days.

Yes if you have mobile number portability in your country

Yes, You can change your network still keep your number. Its called a number portability.

You WILL be provided with the sim / micro sim the new phone uses

PAC

As you are going from PAYG to Contract
make sure you use you TMo minutes as this will be lost

Short story you will have 2 numbers both are live at the start the new "3" mobiles will eventually be killed off, when the transfer happens. The Tmo phone will not have signal bar strength

But I have prepared this for just4u as you are joining my network 3
http://ask.ofcom.org.uk/help/telephone/PAC

As you choice of phone is either the 8Gb iPhone4 (which is 2 years old already) or the IP4S
iPhones tariffs on any every network defy logic and gravity, and if the IP5 were released and it had exactly the same specs as the SGS III it would have a higher tariff

The multi award winning smartphone in 2011 is (was) the Samsung Galaxy S2 I9100
No other phone including the IP4S has won more awards.
Both the SGS II and SGS 3 are superior to any Iphone

So good luck,
If you have not already signed up then there's this