Currently the digital modulation used in telecom is GSMK

GMSK is a form of modulation used in variety of digital

radio communication systems.It has an advantage4s of being

able to carry digital modulation while still using the

spectrum efficiently.

One of the problems with other forms of phase shift keying

is that the sidebands extend outwards from the main

carrierand this can cause interference to the other radio

communication systems using nearby channels.