Another option is frequency narrowing. 20+ years ago FCC required frequencies to be tuned to additional decimal points in certain frequency bands, in essence creating more channels available for licensing. That was mainly for higher wattage transmitters and Cuddelink came along well after that, and lower power.
Seeing how CuddeLink has evolved from 16 to 250 to now 625 channel options, maybe it does relate to narrowing frequencies, which would slow down file transmission unless packet transmission is sped up or streamlined.
Even another option would be like CTCSS on a walkie talkie, telling it to ignore transmissions not including an identifier signified by the second number on single frequency set by first number. This would allow my cell to function on same frequency as another network, yet they become invisible to each other, with an exception not worth mentioning.