I can see why this isn't very pleasant, but there are a lot of things that could cause you this trouble. It could very well be the phone you are using. You can try using an android to see if the problem occurs again. This can also be a glitch for the service provider. Changing your provider is a little more complicated, but it should not take a lot of time. If this doesn't work, another thing you can try is making
free calls online. This way, you won't mess with your provider, and you will also see if the service is the source of the problem.
