Orange San Fran - Unlocked but can't send texts/use 3g etc

[Guest Monty HD]

Hi everyone.

I have tried looking about but can't find the answers I am look for.

Got an Orange San Fransisco. Really like the phone, and have since unlocked it and have stuck a T-mobile sim in it.

Unfortunately, I can't now send any texts (except to 150), use the internet or or make any calls. Does anyone know how I change all the settings/if there is a master setting so it will recognise the fact that it is now on T-mobile and I will be able to use it again?

Please bare in mind I am completely new to Android, so any advice with a step by step menu would be great!

Thanks everyone!