Just wanted to say that I have been using this router (with 2 phone ports) for some months now.
It has the facility to have up to six numbers registered at once.

BTW it can also do direct to IP dialling without any VOIP provider!

It is dear but IMO well worth the price .... it not only has all that is needed for VOIP but also has some very nice firewall/user control features.

Regards,