New flynumber: all calls fail and reason is 'forbidden'

I purchased my Singapore flynumber today and am testing it now. Whether I forward it directly to another Singapore number, directly to a SIP phone or through the PBX to a SIP phone (the PBX even lists sip2sip, so what can go wrong?) no calls come through and the call log says that the reason is ‘forbidden’. I have 10 dollars on my account, so what can be the reason?

Seems number is not active and we will update the account ASAP