It's not necessarily a limitation of bandwidth possible at 900MHz, it's a limitation of the normal equipment deployed and inefficiencies of mesh routing.
Those 900MHz analog phones were also usually low power, low distance, analog only devices with a few number of channels. Try having dozens of those phones all in the same room and see how useful they all are at once.
Those 900MHz analog phones were also usually low power, low distance, analog only devices with a few number of channels. Try having dozens of those phones all in the same room and see how useful they all are at once.