Out of Pocket

I heard a colleague of mine use the term "out of pocket" in our MS Team group to mean that he was away from his desk and not as available. I had never heard the term. 

I found this definition, "‘Out of pocket’ is out of range" from https://www.quickanddirtytips.com/articles/3-meanings-of-out-of-pocket/ 

I read somewhere else that said it meant that he was using his mobile device to answer any queries. That he was not at his computer. I like this meaning the best. It is what I mean when I use this phrase.