It looks like if I solved my problem. The key hint was Thomas' remark that in the event of WAN failure, protocol bindings fail over to the working WAN. In my setup I had Network Service Detection enabled with Default Gateway selected as the target for the ping attempts. What I was observing in the System Log were strange messages of "NSD FAIL WAN[1]". I did not understand these because WAN1 was working fine. Now I had the idea to try to ping the Default Gateway of WAN1 manually in a command prompt window and obtained "Request timed out". I guess this machine simply drops ICMP packets but works OK as a gateway since I do not experience any problems using WAN1 for internet access. Now I disabled Network Service Detection and since then my IP-Phone keeps being registered via WAN1 with my DSL provider. Best regards, Felix ... View more

Thomas, are you still there? I have to admit I changed the DNS settings back to "automatic" out of "aestetical reasons", and because I didn't understand why DNS plays a role (we are dealing with IP addresses, not domain names). After "Registration failed" I switched back to 8.8.8.8/4.4.4.2 and rebooted. First again "Registered", then after some minutes "Registration failed". ... View more

Magic! Thanks so much, Thomas. Enjoy your holiday ... View more

Firmware is v4.2.1.02 (Jan 18 2012 14:10:55) I already checked for more recent firmware. My version seems to be the most current. I will reboot the router and report the result here as soon as it is up again. ... View more

Phone still reports "Registration failed". ... View more

Yes. Internet works fine with WAN2 (cable). ... View more

Sorry, I don't understand the NAT issue. I would assume there is no difference. The cable modem is a Cisco EPC3208. It has been set up by the technician when he installed my cable connection. I don't have the admin password. ... View more

These are the IP addresses I receive when both WANs are enabled. Does it make a difference whether the RV042 gets the IP or a "computer connected directly" to the cable modem? ... View more

No. Never. ... View more

To clarify: the phone is only working with WAN1 enabled and WAN2 disabled. With WAN2 enabled and WAN1 disabled, the phone reports "Registration failed". (with protocol binding adjusted to WAN2 when enabled). Interestingly enough when WAN1 is enabled and WAN2 disabled but protocols are bound to WAN2 the phone successully registers. How can this be?! ... View more

Thomas, I really appreciate you working on the US holiday. To be specific here is my setup: WAN1 - DSL            WAN2 - Cable |                              | |_________________|                |           RV042                | LAN3____|_____[...] | | Phone(192.168.1.16) ... View more

Hi Thomas, thanks for responding. In addition to the rules I specified above, I added the following rules: All Traffic [TCP&UDP/1~65535]->"myPhoneIP"~"myPhoneIP"(0.0.0.0~0.0.0.0)WAN1 [Enabled] All Traffic [TCP&UDP/1~65535]->0.0.0.1~0.0.0.254("myPhoneIP"~"myPhoneIP")WAN1 [Enabled] Result is again: Phone reports "Registration failed". Anything else that I could try? ... View more

I am still hoping for some help. My problem is still unsolved. If I did not make my problem clear enough, please ask for further information. Or, if there is some principle limitation that prevents binding VoIP traffic to one WAN port, please let me know so that I can take further steps (terminate phone service with DSL provider). Currently I cannot use my fast cable connection if I still want to be accessible by phone via my slow DSL connection. Regards, Felix ... View more