My internet-box does now support voip. Also direct support of dect handsets is good. The problem is I can only run Swisscom's sip/voip service on their own box. As I have multiple SIP providers, I switched to Gigaset. Their voip/sip and pots support through the 300 series was a good solution. I now run voip/ sip for 3 providers with no problems. Do let me know if you found a wired solution.