Why does it say "Number Barred" every time i try to place a call with my T-Mobile?

[SunshineJ]

I havent used my number since november and have had it outside the UK for that time. Now i need to make calls while roaming but it says Number barred every time i try an place a call

[dsgrieve]

If it is a PAYG SIM, it might have call barring set - meaning they won't let you call out when roaming.

[Unregistered]

ik ben luna mombers