I have an existential doubt, I know how is the flow to request and get a delivery report from SMSC when the ESME send a submit. But, how should be the behavior when the registered_delivery is requested by the SMSC (to an ESME)?
Should ESME send deliver_sm? According smpp 3.4 (specification that I'm using) deliver_sm is not issued by the ESME. So, What I should do to send delivery report to SMSC?
I will quote SMPP 3.4:
4.6.1 (“DELIVER_SM” Syntax):
registered_delivery — Indicates if an ESME acknowledgement is required
2.11 (Message types)
For a fixed SME (i.e. ESME) the circumstances in which an SME Delivery Acknowledgement may be sent are beyond the scope of this specification
You will have to communicate your question to the SMSC owner in order to clarify what exactly is the information that they request. For example, if the deliver_sm packet with registered_delivery is an MO message, you could send back some event notification upon delivering this MO to its final recipient.
In any case, you should never use deliver_sm for SME acknowledgement notifications (as you well pointed — deliver_sm is not issued by the ESME). There is a special esm_class flag that you can set in submit_sm that should be used for this:
5.2.12 (esm_class)
x x 0 0 1 0 x x — Short Message contains ESME Delivery Acknowledgement
x x 0 1 0 0 x x — Short Message contains ESME Manual/User Acknowledgement