Is it a scam if an Army recruiter calls about trying to get prior service members back into the military?

Probably just pulled your name from an old IRR roster. Recruiters have to make those numbers somehow

That call you got could be legitimate. Recruiters do sometimes reach out to prior service members, especially when certain roles are in need of experienced personnel. However, it's wise to take a few extra steps for peace of mind.

One option would be to verify the number itself. Platforms like https://whocalled.co.uk are useful for checking if the number has been flagged as suspicious by others or if it’s linked to any official recruitment efforts.

When I ETS’d in order to go to ROTC, I was in the IRR for approximately 2 weeks. In that span I received 2 letters and 5-6 phone calls from recruiters asking me if I wanted to continue my career in the Guard/Reserves.

It’s likely legit. Uncle Sugar has spend hundreds a thousands of dollars training and taking care of you. He’d rather not lose out on that investment if at all possible.