If you have call quality problems with one specific number or a specific type of number (e.g. a particular country or mobile numbers) but all other calls are fine, then it might be related to an issue with one of our suppliers. In this scenario we may change the route your call takes to determine if the call route is the issue.
It is also worth noting that the quality problem may be related to the other person’s phone or phone network. Some mobile phone networks may have poor coverage in some areas, similarly it can also be the case that some foreign telephone networks have old and poor quality networks.