Trilogy spanning past, present and future
I am looking to identify a book trilogy I read. I am pretty sure I read it in the early 2000s, but I don't know when it was written. If I had to guess, I would say it was likely pretty new when I read it (possibly written in the late 90s). I thought it was a Twilight Zone story but I haven't been able to find any of those that match my memory so it is possible I am mistaken on that point.
Each book in the trilogy covered a different time period. One was the past (about medieval times) , one the approximate present and one in the future.
I believe there was at least one character who is involved in all three books (Let's call him <PERSON> since I can't remember his name and having a name makes this description easier to read). I know that in the future book he is disembodied and he possesses a woman (Let's call her <PERSON>). Many people in that time have phones implanted in their jaws so <PERSON> is able to talk to <PERSON> without people thinking she is crazy.
I think <PERSON> may have been alive in the past story, but I don't remember for sure.
I think that in the future story, someone is planning to force another disembodied soul into an unwilling person's body. 944
I think <PERSON> and <PERSON> work together to try to stop this.
The trilogy may have used the theme about magic really being science sufficiently advanced so as not to be understood. I.e. There may have been "magic" in the past book but the same things were seen as science in the future book.
So the parts that I remember clearly are that it was a trilogy with each book set in a different era and in the future a disembodied spirit possesses a woman and they work together. Also, in the future many people have phones embedded in their jaws.
I have tried these Google searches:
1. scifi book trilogy past present future - unfortunately I am not looking for <PERSON> album "Trilogy: Past Present and Future"
2. scifi book phone embedded in jaw - Results show Warship, Red Moon, The Circle Trilogy, Harper Hall Trilogy, The Sentinel, etc. I haven't yet seen any that match what I remember. 322