Question re disconnecting landline business service

Yes once you port all numbers from an account the account closes automatically, unless there was another AT&T service, like internet, connected to the account. In the past you had to pay a closed account by mailing a check once the final bill arrived.

You've posted in the residential forum.  Unless business lines are different porting doesn't disconnect the old service.  I think you'd better be sure or you'll be still paying a bill to AT&T.  

I can tell you for residential service they don't prorate.  I would assume business would be the same.  

To my knowledge AT&T does not prorate service charges at all, even if you're only two days into the cycle. Likely they'll expect full payment of the bill and chalk it up to poor timing. You'd need to contact customer service for a more exact answer to that one though. Rules could be different for businesses vs consumers.

Ok thanks.  Would you know if we'll get a prorated bill? The bill we just received is in advance for the period Feb. 17 - Mar. 16, we moved service to the new provider on Feb. 18.  I would prefer not to pay the bill if I can avoid it because then we'd be waiting on a large credit.