That will not necessarily be a feature of your Nokia 'Phone...
It will be more to do with the signal strength of the particular Service Provider (Network Operator) that routes your calls - Switch between Vodafone - 3Mobile - O2 - T-mobile etc and one of them will have the best signal and another the worst.
You can either move house or change service provider or stick with things as they are.
Good luck...
Peccavi, February 2013
