Many licenses in the A, B, and C bands have now been subdivided - mostly by their licensees selling part of their allocation. Some are now assigned by BTA or are less than 30MHz. The C band is the most notable division, with the FCC auctioning 10MHz chunks as C3, C4, and C5, or 15MHz divisions as C2 and C1.
Note that the FCC does not divide PCS into discrete channels - leaving that to the carriers based on their choice of technology.
Nextel has requested that the 1900-1915MHz paired with 1990-1995MHz bands be granted to them in exchange for their SMR licenses due to interference between Nextel and Public Safety radio in the 800 MHz band.
CDMA frequency display.
CDMA carriers are 1.25MHz wide and in the arrangement above are allotted 25 channels each. Each block has a guard band at the top and bottom to prevent interference with neighboring carrier blocks. Each CDMA carrier can carry multiple calls through Code Division of the signal.
TDMA frequency display.
TDMA carriers are 30kHz and divide the blocks into channels. The A, B, and C blocks have a calculated 499 channels each (unless the carrier has sold of a portion of their frequency) while the D, E, and F blocks have 165 channels each.
Each TDMA channel can carry multiple calls through Time Division of the channel into slots.
GSM frequency display.
GSM carriers are 200kHz and divide the blocks into channels. The A, B, and C blocks have a calculated 74 channels each (unless the carrier has sold of a portion of their frequency) while the D, E, and F blocks have 24 channels each.
Like CDMA and TDMA, GSM allows multiple users on each channel through sharing.