There is a prison near Tehachapi, but not in Tehachapi. The prison is not the most distinctive thing about the community. The call could not have originated from the prison as all calls originating on inmate phones have an automatic announcement telling the receiver that the call is from a state prison inmate. The repeats throughout the call. In addition, all calls originating from the prison must be placed collect.
While it is true that inmates sometimes obtain smuggles cellphones, this is rare and they never have them for long before being discovered. This number has been placing calls for far too long for that to be the case...plus...what would be the point.
Called back the number and the recording said that the number has been changed or disconnected and is no longer in service. Someone is probably tranmitting a false caller ID to solicit or get information.