For the last few weeks, when I call most numbers, I get a message which says "unable to route your call. Please consult your service provider." However, the call then goes through and the number I'm calling rings. I also sometimes get a message "this number does not exist. Please re-check the number or consult directory enquiries." However, the call then goes through. This has only recently started happening and occurs on most numbers I phone. How can I avoid these messages?