PCN (Personal Communication Network) is also known as
GSM 1800. It uses the radio frequency of 1800 MHz as compared to the original
GSM using frequency of 900 MHz.
It gives higher call quality than GSM 900, but half the number of calls per transmitter.
See also:
http://www.tmtouch.com.my/corporate/pcn.html
http://www.tmtouch.com.my/corporate/gsm.html
http://www.tmtouch.com.my/corporate/compare.html