The rules are different in different areas and with different groups. I grew up in an area with lots of Amish neighbors and they generally speaking did not use technology but there was at least one house I remember having a phone and even one that had a windmill to generate electricity though I don't know what for.

Amish men, at least in my area, would also occasionally go to bars, the whole family went to stores, etc. where they would be able to use technology like phones.

And I'm fairly certain the Amish around me in Western Pennsylvania/eastern Ohio were some of the stricter ones whereas, I've heard, communities in Minnesota for example are less strict and will even have things like TVs in their house.