Which modem do you have?
There are presently two satellites in use (EchoStar 19 was just launched and is not yet in service.
Spaceway3 is located at 95'W. Users with the HN9000 modem are serviced by Spaceway3
Echostar17 is located at 107.1'W. Users with HT1000/HT1100 modems are serviced by Echostar17.
If you are pointed due south I would guess you have the HN9000 Modem and one of the monthly refill plans