Just to give an update.

I received a new Linksys ATA from Voipo which is working.
I have made all the changes in my Uverse router to forward the ports requested.

But I am still having issues. Some callers are complaining they are getting a disconnection message sometimes. Sometimes the phone will ring and we'll see CID, pick up the phone and it will then be dead air and the failover phone (cell) will ring. Some callers are saying the voice quality is horrible. Still having random beeps on other side as well.
Still not happy with this service that I paid 1 year in advance for and probably can't cancel it.