What brand and model router are you using? You may want to try disabling SIP ALG in it. Alternatively, you can try voip4.freephoneline.ca:6060 for the proxyserver. The purpose of voip4.freephoneline.ca:6060 is to circumvent faulty SIP ALG features in routers. Then reboot your router (wait for it to be fully up and running) follow by your IP phone.
I have no experience with that IP phone, and I don't see an emulator online for it. If you can find similar settings that apply to your IP phone, I would use the instructions from these two posts as general guides: visit
http://forums.redflagdeals.com/anyone-h ... #p26234003 and
http://forums.redflagdeals.com/freephon ... #p26808549 (follow the steps carefully, step by step, in the order listed, if you can). The settings described should be similar and also apply to your IP phone.
Also, please check FPL's registration in the device as well.
Please note that only one registration per FPL account is allowed at any time.
When there are multiple devices/softphones using the same account, only the most recent registration is valid. The previous device will lose registration (despite the device's registration status potentially indicating that it's registered) and incoming calls will not work on it. Registration is required for incoming calls but not for outgoing calls. In other words people sharing their FPL accounts or otherwise trying to register their FPL accounts with smartphone SIP apps/desktop apps while simultaneously using the same FPL account on their ATAs or IP Phones are out of luck for incoming calls.
Also, these three timers are important with respect to avoiding temporary IP bans (if you're able to register and retain registration, then that's not the problem).
https://support.freephoneline.ca/hc/en- ... redentialsi) Registration Interval:3600 seconds (1 hour)
ii) Registration Expiry: 3600 seconds (1 hour)
iii) Failed Registration Re-Try Interval: 120 seconds
Hopefully, someone with experience with your IP phone will respond since I am probably out of further suggestions.