While both the RJ48C and RJ48S use the same connector type, they actually have different pin assignments so they cannot be interchanged with each other.  The RJ48C uses pins 1/2 and 4/5 as shown in the following diagram:



Where as the RJ48S uses pins 1/2 and 7/8, as shown in the following diagram:



Telect's T1/DS1 Backhaul demarcation panels support the RJ48C pinout.