Is it dangerous when your microwave interferes with your landline phone signal?

I've noticed recently that whenever I talk to my boyfriend on his house phone and he puts something in the microwave, the phone starts sounding really "crackly". It's hard to hear him and it almost sounds as if the phone is going in and out of reception. This even happens when he's in a completely different room and his parents use the microwave in the kitchen. It might sound silly, but I'm concerned that there's some sort of radioactive waves floating around his house whenever the microwave is turned on. Does anyone know anything about this?