Your call to an inmate may be blocked, but if it goes through you probably won't be charged, however...
Locate the state, then the city or county where you think they are being held.
Although the FCC and other agencies are looking for ways to end illegal cell phone cummuncations to and from lockups, you are not likely to get in any legal trouble for calling an inmate who has a contraband cell phone inside. The laws may change in the future, but right now the focus is on testing and implementing new technologies to eliminate transmissions.
Currently, the jail or prison may decide to deny you future phone calls from the inmate or visits to the facility if you get caught.
To begin your search for an inmate or arrestee, or locate any jail or prison here: