A base station determines occupancy of a channel used for message communication and transmits channel occupancy data to access terminals operable to transmit messages via the channel. An access terminal receives characters for sending a text message via the channel and determines whether the channel occupancy exceeds an occupancy threshold. If the channel occupancy exceeds the threshold, the access terminal transmits characters of the text message to the base station via multiple messages. Each of those messages including a number of characters that does not exceed a maximum number of characters associated with the threshold. If the channel occupancy does not exceed the threshold, the access terminal transmits characters of the text message to the base station via a single message so long as the number of characters does not exceed a maximum number of characters for sending a complete text message to the base station via a single message.