Question: In mobile originated SMS transfers via CS domain, what is the correct sequence when reusing the same RR connection (in A/Gb mode) for a new short message transfer?
Option 1: Transmit CM SERVICE REQUEST after final CP-ACK for old MM connection, then transmit first CP-DATA on new MM connection.
Option 2: Transmit final CP-ACK for old MM connection before transmitting CM SERVICE REQUEST for new MM connection.
Option 3: Transmit CP-ACK for old MM connection simultaneously with first CP-DATA on new MM connection.
Option 4: Transmit CM SERVICE REQUEST for new MM connection before final CP-ACK for old MM connection, allowing CP-ACK for old MM to be sent before first CP-DATA on new MM connection.
Explanation: This correct sequence ensures continuity of the RR connection while maintaining proper protocol for initiating a new MM (Mobile Management) connection. It prevents potential conflicts between old and new message transfers, respecting the rule that the MS shall transmit a CM SERVICE REQUEST for the new CM connection before the final CP-ACK for the old MM connection is transmitted.