SPA2102 behind router fax problem

[VitaliyKrym]

I'm having problems with fax send/receive when SPA2102 is connected via D-link router. Faxes just cannot connect or recognize each-other. No any problems if connected directly to cable modem as a bridge. Voice function works fine no matter how it is connected. Is it fixable?

[Daniele Giordano]

Which fax method is configured? T.38 or RTP pass-through?

If you use T.38 see this note:

Outgoing T.38 fax through symmetric NAT routers WILL NOT work, since the external called party is responsible to start communication with the fax answer tone indication. On the other hand the external endpoint must wait for the internal endpoint to send a T.38 packet in order to know where to send the fax answer tone indication (source wiki.innovaphone.com).

Regards.