Yes - but the radio knows when it last heard from the "mother ship", and when it's timer expires, it can decide to no longer provide you data. It can LOOK like it has two-way, but not have it in actuality. A trick of electronic logic.
Could certainly be, but with the experience of two different radios, and a lot of internet searching............I've got a different conclusion. As I previously mentioned, I had two radios (vehicle & Garmin 696) put on a five month hold, due to an accident, in which I couldn't drive or fly. XM will go five months max. without a new activation charge
At the 2 1/2 month point, a friend flew my plane on a cross country, and I went as passenger. I was surprised that the XM weather/radio was still working. At 4 months, when once again using my truck, XM was still working. In the meantime, these two radios had been totally off.
After a search for answers, it appears that XM sends out a shutoff command so many times an hour, and for so many days. If a radio has been totally powerless for several months, then it misses the command. Due to bandwith, these commands are not continuous.
In the meantime, XM can offer a two week special, in which the radio is one again activated. But then the "off" command is resent. That way, you don't end up with "freebie" XM for an unlimited time. If's that's done on purpose, which is a good idea..........I'm only guessing.
In my case, I re-signed with XM during that fifth month. But in the meantime, the truck radio remained on, and the 696's was only briefly interrupted.
Now, thanks to a 60mph encounter with an "uninsured" deer on my motorcycle, I'm going through the same thing all over. I'll let you all know in two or three months.....as to whether the XM is on or off.
L.Adamson --- RV6A