The Voipo Customer Care folks have been excellent to work with. My AT&T DECT 6.0 phone would not display the caller id on my 701 adapter. So they sent me a 502 adapter and it worked! I think the issue had something to do with the DECT phone. Voipo's service and adapter have exceeded my expectations! I almost never can say that about any company. Amazing. I am so very happy that I dropped the AT&T land line to go with this solution.