Some electrical devices can cause interference on your phone line and therefore cause dopouts in somecases.
In my case plugging a DECT phone charger and the router charger into an extension and locating it away from the master socket reduced the interference on my line.
Using a good quality active filter rather than a cheap one can also help cut out interference.
It's hard to tell if that's what's happening to you without more info. Post your line stats click here