An improved mobile dial telephone system
H.W. Nylund, R. M. Swanson · IEEE Transactions on Vehicular Communications · 1963
Most of the mobile radio telephone systems now in use depend upon operator call-handling and require the mobile subscriber to work push-to-talk. In addition, although the mobile set may be equipped to operate on several channels, it can be selectively called on only one. If that one channel is busy, base-to-car calls are blocked even if other idle channels are available. All of these features have combined to make mobile telephone service less convenient and useful than wire-line telephone service, and this has seriously hampered its growth.