Uplink congestion control based on session initiation protocol (SIP) messaging includes receiving SIP messages from user equipment devices (UEs) via established wireless uplink connections; and monitoring a rate of the SIP messages received from the UEs. Uplink congestion control further includes identifying whether the rate of received SIP messages exceeds a first threshold during a first period of time; and sending SIP response messages to the UEs to reduce congestion on the wireless uplink connections upon identifying that the rate of received SIP messages exceeded the first threshold over the first period of time, where the sent SIP response messages instruct the UEs to resend the SIP messages after predetermined time delays.