Thanks Deepika for your reply. Gone through the SMPP spec doc, it says DELIVER_SM PDU helps to capture the customer response. But if message_id will not get generated for customer response which is DELIVER_SM PDU by service provider, how to correlate MO with ACC?

Hi, I would like to know how 2 way SMS works in SMS channel delivery. What is the PDU that is used for MO (customer responses). And where the response is stored or which field of the PDU is used to stored the customer response.