Last week I got connected by a new ISP, but my phone number wasn’t ported yet. This weekend I struggled to get it working on my old router. I wanted to use the old one, because the ease of use and also because the new router couldn’t be mounted on the wall.
After some struggle, I managed to log in VOIP service, only after calling the line was dropped. My router didn’t have the necessary codec to ‘talk’ with the VOIP server. The standard router software didn’t have the codec, but my old provider has software for the router on their site which has the necessary code. Now I can finaly call for free within The Netherlands.