Is it permissible to break the fast after the mosque's call to prayer, or is it obligatory to wait until the television's call to prayer if there is a two-minute difference between them?

If the mosque's muezzin is trustworthy and gives the adhan (call to prayer) at the precise entry of the time, then it is permissible to break the fast as soon as you hear his adhan, and the fast will be valid. However, if the muezzin gives the adhan before the entry of the time, then one must wait until sunset is certain.