In article ,
john smith wrote:

Some posters have written that XM goes inactive if you haven't used it
in so many days.
How do they know when you use it? It is a one-way system!!!
You call to activate it and your receiver unlock code it included in the
downlink stream, correct?
Why would XM delete your unlock code from the downlink stream if you are
paying your subscription?

Alt.radio.satellite is another place you could raise these questions.

It's unfortunately a pretty dumb group overall; you'll want to create a
filter that only allows XM-related messages through, and even then a
fair proportion of the messages will be junk.

But I don't know of any other group that's helpful for XM-related
technical questions (except maybe comp.dcom.telecom, which just
generally has a lot of technically savvy electronics types).