I brought a new sim card with credit and goes to ring out and it says mobile network not working when I go to ring it it says

[sarah-louise]

I got a new sim card but it won't let me ring out or in its saying its an invalid number I've asked the phone company and they said its still processing I've never has this problem with any sim cards before

 

[Someone Somewhere]

How long has it been since you first powered up the phone with it inserted? It can take anywhere up to a few hours for it to propagate through their system.

Depends how their system is set up.