I use voip.ms as my voip provider and Zoiper Biz as my softphone. I had Zoiper configured to access the chicago2.voip.ms server and that had been working fine for years. Recently, I configured my router to use the 184.108.40.206 DNS server and forced my computer to get DNS entries from the router. This has not led to any rpoblems, until yesterday…
When I tried placing a call, I got a SIP 503 - DNS timeout error. I reached out to voip.ms and they suggested using the IP address, instead of the domain, and that worked. Strangely, I was able to successfully ping the server from my computer. I posed this question to Zoiper and they responded: This error and the fact that you can connect to the server by IP address indicates that the cloudflare’s DNS server is not aware of the domain which you are using. There could be many different reasons for that. However I can only suggest that you either use the IP address or return the standard DNS server of your ISP.
I am not sure who to believe at this point. While I can make calls, I would like to understand the cause of the problem in case something like this crops up again. Any ideas/suggestions?