For what it's worth, I have 2 accounts with a PAP2T on one and a 502 on the other, both in tandem.

Although the PAP2 has never missed, I see this morning that the 502 has been up and running and registered for the last 19 hours.
Sure looks good.

PAP2T line 1=5060 line2=5061

502 line1=5079 line2=5062