The 23-hour lockdown is real, but some cells have a payphone in them. If that is the case then there are no limits (except the prepaid money on their books).
https://www.inmateaid.com/ask-the-inmate/i-would-like-to-know-how-many-calls-can-an-inmate-make-per-day-and-if-it-is-policy-for-them-to-be-locked-in-23-hours-a-day-and-allowed-only-1-hour-out-per-day-in-a-certain-area-in-baltimore-county-detention-center#answer
Accepted Answer Date Created: January 06,2022