CS50 and CS55: Comparison
The headsets look identical and operate in the same way. However, they operate on different frequencies. The CS50 operates at 900 MHz and the CS55 operates at 1.9 GHz. The CS55 is specifically designed not to interfere with other wireless office products. Other differences are the talk and standby times. The CS50 battery provides up to 8 hours of talk time and 40 hours of standby time, while the CS55 battery provides up to 10 hours of talk time and 50 hours of standby time.