While I'm very happy with my N9, I do have huge problems with SIP-telephony over Wifi.

My N900 had accepted wifi bugs, making serious SIP-telephony over Wifi impossible (stuttering, channel loss), I was hoping that the N9 would have reached the same quality as my old Symbian-based E51.

The N9 is more useable than the N900 for SIP-telephony over Wifi

I use a AVM Fritzbox 7170 for years and recently tried a D-Link DIR-645. Using the Fritzbox I often get package loss and general non-ideal voice quality, and always missing the first missing seconds of the talk, using the DIR-645 I've got a better over-all quality, but frequent complete connection dropout, especially when answering a call.

Anyone here who has a setup where error-free serious SIP-over-Wifi telephony is working with the N9? Which equipment do you use, which Wifi channels etc.?

ATM I'm considering to revive my E51 and degrade the N9 to a toy. :-(