Call forwarding for an account that is not linked to a phone

My cell phone was very recently discontinued from service

Explain? 

AT&t doesn't care whether you keep an old postpaid  plan that doesn't have a data plan. But you have to have a compatible phone which means a basic talk and text phone and not a smartphone.  (Still sold by at&t, mostly on the prepaid page)

Or if you've managed to hold on to the older $25 a month prepaid plan which was talk only, text package could be added. No data was included.  AT&t prepaid does not restrict your phone to a basic phone.  

because the account from 2011 only covers calls and text, which is my preference.

Okay.... 

The account remains active, but call connections do not.

Why not?   Are you using an incompatible phone? AT&t shut off it's 3G service over a year ago. If you are using a 3G only phone you would have to replace it with an LTE phone. That is capable of voice over LTE service.  

May I have calls to the phone number forwarded to a different phone on another provider and stay on the existing account? The answer may require reference to the account number.

AT&t can permanently forward your voice calls to another AT&t phone on the same account only. Text messages cannot be forwarded.   Why don't you just replace the phone? And soon otherwise AT&t can and has closed accounts that do not have an active and eligible phone attached and working.