I have a vodafone HG556a modem/router that I no longer use as I've made the switch to VDSL2. A few days ago my Linksys AG310 analog telephone adapter starting blowing smoke out the back so I thought I would replace it by connecting the HG556a to my VDSL2 modem in bridge mode and use this for my VoIP system.
I've tested out the SIP function before in the HG556a and successfully got it to work when I had an ADSL2+ connection. However, now the 'Active SIP Account' box won't check after telneting in and following the instructions given in this thread.
So my two questions are: Does this procedure of checking the box via telnet require that the modem is connected to an active ADSL connection? And, can the HG556a operate in bridge mode when using SIP?