Aspects of the present disclosure propose systems and methods for managing assignment of short message service (SMS) message identifications (IDs) in a multimode device (e.g., mobile station). The proposed methods ensure that a unique message ID is assigned to each SMS transmitted by the mobile station (MS). Each retransmission of the SMS messages may be assigned a message ID similar to or the same as the previous transmission(s) of the SMS message. As a result, a network messaging center may be able to identify duplicate SMS messages that are marked with unique message IDs even if they are transmitted on different air interfaces and/or by different modems (modulators/demodulators).