DSL issue

I’ve been having a curious problem with my DSL service in recent weeks: whenever I receive or make a voice call on my telephone line, the DSL signal is disrupted for at least several minutes. Often it returns by itself, after a few minutes, but sometimes I have to power-off and power-on the DSL modem and the wireless router (clue?) that I use to get the signal to my laptop before it recovers. I could contact Verizon–now AT&T in my area–about this, but it’s quicker to post a note here and hope someone might know what the problem could be. Anyone?