Perhaps you are confusing that each GSM transceiver (TRX) provides 8 time-division channels with call capacity, but most cells and specifically the BTS in GSM parlance, especially any in a well populated area have/had way more than one transceiver. 30-40 was not unheard of in later equipment, though 10 or so was more typical. Late in GSM's life there was another technique to squeeze more channels, OSC.
Furthermore those 8 TDMA slots could be split in 1/2 or 1/4 with lower rate codecs, so it was more than 8 per TRX as well.
anything bigger than a picocell would carry way more than 8 simultaneous calls.
> Some large conferences have had base stations with their range measured in single digit meters (<30 ft)
Femtocells are still a thing today. Not so much to do with frequency capacity.