SIP <-> POTS phone adapters behind NATS / firewalls

Do the generally-available SIP - to - POTS (analog) phone adapters, such as the Linksys PAP2-UA and others, generally work correctly when hiding behind NAT boxes or firewalls?

Our PBX is visible on the net, and two of our users are at home behind home DSL or cable routers. They are currently using X-Lite 3.0 softphones successfully, but they would rather have something that works with a normal phone, mostly so they can use cordless phones anywhere in the house. I just want to make sure I get them something that will work behind their DSL / cable boxes as well as X-Lite does.

Thanks…

Yes they will work quite well. Turn on STUN on the device and on * set qualify=yes and nat=yes.