I want to share my experience with TekSavvy, which is a misnomer, by the way.
My mom got tired of being shafted by Telus, so I persuaded her to switch to TekSavvy Internet. In the end Telus ended up cutting her phone off too, even though she didn't request it. Instead of dealing with Telus, I told her to get the $10 plan from Teksavvy.
Everything was good while she had the temp phone #. Then on the porting day, her ATA stopped working. Two days of pointless troubleshooting with their tech support yielded nothing. They just read from the script asking to do endless reboots and resets. Thank God for these forums - I was able to find the solution. I installed Zoiper and verified her SIP username and password are correct. After I was able to register her account on Zoiper and tested it, I did the following steps (after uninstalling Zoiper):
1. Connect a PC to the LAN port of the HT502 and leave the WAN port vacant.
2. Factory reset the HT502 by pushing the reset button until the lights go off.
3. Once the HT502 boots up, turn the PC on - it will grab an IP from it.
4. Open a browser on the PC, go to 192.168.2.1 and enter the factory admin password (admin)
5. Go to ADVANCED SETTINGS and delete the URL for "Config Server Path" - very important!
6. Go to BASIC SETTINGS and change your "Device Mode" to "Bridge" - now you can use your ATA between router and PC.
7. Save and reboot both the HT502 and your PC. Connect the WAN port of the HT502 to your router - HT502 and your PC will grab IP's from the router.
8. Now you can access HT502 from any PC on your network. I added DHCP reservation for it.
9. Open your browser and go to the new IP for the HT502. Configure FXS PORT1 using settings from TekSavvy's site.
The only thing I did different was change "NAT Traversal" to "Keep Alive", but I am not sure it is necessary.
10. Use username and password that worked with Zoiper.
In my case, apparently, TekSavvy's auto-config was using temporary phone and password, instead of the ported one.
By using "Bridge" mode, my HT502 and one PC use only one port from the router. Here is my final setup: