Tips based on using a c. 6-7 year old satphone in a small biz jet; newer satphones / newer, bigger a/c may be better, I have no experience with them sadly!
1) try to get an external (to the aircraft) aerial fitted, if you are going to rely on the phone - e.g NAT HLA. Trying to get & maintain reception using just the antenna in the phone when inside the aircraft is nearly impossible in my experience.
2) some sort of jack to use it with your headset will be invaluable - either that or use it in the cabin. The ambient noise coupled with the small, slightly crappy speakers on the phone makes it very difficult to hear what the other person is saying, particularly if they are in a place with lots of background noise.
3) invest in some sort of (preferably) hard carry case, keep it in the same place on board all the time & make sure it’s charged! We tried to keep ours in a particular locker on the flight deck, and there was an unofficial sop of checking the battery on the first flight of the day (day before if we knew we were doing a long ranger).
Good luck!