RJ11 to RJ11 uses 4 wires straight through (Pins 1-4 RJ11 to Pins 1-4 RJ11) ALL LENGTHS AVAILABLE. RJ11 to RJ11 uses 6 wires straight through (Pins 1-6 RJ11 to Pins 1-6 RJ11) ALL LENGTHS AVAILABLE. RJ45 to RJ11 uses 4 wires straight through (Pins 1-4 RJ11 to Pins 3-6 RJ45) ALL LENGTHS AVAILABLE.
eBay