Greetings from our team!!!
Since MNP started materializing in INDIA, there has been lot of interest growing on MNP call flows. We have received quite a few requests for MNP SMS flow.
Here we have tried to explain basic MNP SMS flow. Terms which came into existence due to MNP are already explained in earlier posts.
So let us start.
Assumptions: A and B both are Vodafone Delhi Subscribers (Ported In or normal).
A is postpaid number.
Let us now go through signalling flow.
1) A sends an SMS to B. Mobile Originated Forward Short Message (MO-FSM) is send to STP/MNP with destination as SMSC address(SMSC GT). SMSC address is already stored in SIM. MO-FSM also contains B number to which SMS is sent.
2) MNP check its database attaches RN/LRN to B number and forward MO-FSM to SMSC.
3) SMSC acknowledges the MO-FSM by FSM Response to MSC. This three steps complete the MO leg of SMS Flow and handset receives an indication "SMS sent" at this point of flow.
4) Step4 marks the beginning of SMS terminating flow. SMSC checks this is our own RN/LRN removes RN from B number and sends Send Routing Info- Short Message (SRI-SM) to STP/MNP. This message can be directly send to HLR also that depends on network topology.
5) SRI-SM is forwarded to HLR with B number.
6) HLR responds SRI-SM Response with the VLR address where subscribers is currently registered and IMSI of B number.
7) On receiving VLR address now SMSC knows where to send MT-FSM. SMSC send MT-FSM to that particular VLR with B number IMSI and SMS data.
Here after MSC tries to deliver this message to B Subscriber using standard MT SMS flow.
8) MSC/VLR acknowledge SMSC by MT-FSM response which contains status of MT SMS.
i.e delivered or failed cause if SMS is not delivered to B number.
This sums the SMS flow in case of MNP,our main motive was to highlight the difference between normal and MNP SMS Flow. Hope we fulfilled that and hope this post was informative for you.
Keep checking for new posts till then HaPPy Reading.
Comments/Criticism/Queries/Appreciations are most Welcome as they are lifeline of this blog.
ChEEEEErS
Telecom Tigers Team
telecomtigers@gmail.com
http://homepageforu.webs.com/
http://homepageforu.webs.com/
In Step 4/5, if the SRI-SM is destined to a different operator than the Home operator, doesn't it require the attached RN/LRN to the B number for correct routing to the HLR?
ReplyDeleteDear Friend you are absolutely correct ...
ReplyDeleteBut above post was to discuss SMS flow in case of Ported in or Normal Subscriber.
Certainly LRN will be attached in case of SMS to other operator
ChEEEErs
Telecom Tigers Team
Hi
ReplyDeleteCan you please send USSD (Unstructured Supplementary Service Data) MT MO SMS data flow for USSD server.??
Dear Telecom tigers ,
ReplyDeleteWe have a ICR implementation with other operator for our circle , kindly explain in that case for a prepaid subs how will SMS flow . MSC in use is the other operator MSC . We are having direct connectivity b/w our STp and their MSC so our MSC is bypassed ? CAn u please share how and where will the SMS charging and CDR generation will be done .
Dear,
ReplyDeleteYes in this scenario your MSC will be bypassed.
In case of Prepaid subscriber before "Forward SM" to SMSC there will be your IN/SCP enquiry.
Here the charging takes place.
Regarding CDR it will created only in other operator MSC.
great site yar
ReplyDeletecan any 1 tell me what is the benefit of sending ussd over smpp.and what is the flow
ReplyDeleteDear Telecom Tiger,
ReplyDeleteHow the SMS MT flow if A is subscriber of other operator at different country and B is ported out from Donor to Recipient .
A Operator route the MSISDN of B to Donor network /STP. SMSC A send SRI to Donor Network.
What Donor will do ? the SRI will fwd to HLR of Recipient by Donor or else ? pls help to explain or through signaling flow will much better, Thanks in advance.
@Anonymous:Dear,
ReplyDeleteCan u explain your query with examples its not clear.
Dears,
ReplyDeleteWhat about international SMS terminated to subscriber B who is ported-out, in normal situation its understood from above flow, but what if operator is using anti-spam? so first the SRI_SM will reach GMSC/STP, how it should be handled from there? if its sent to SRF first, then SRF will handle it and return SRI_SM_Resp. and in this case anti-spam is eliminated from the whole flow, at the same time, if GMSC/STP forwarded the SRI_SM toward anti-spam first, then anti-spam will handle it by sending it to HLR and when getting a reply, anti-spam will reply the originator using his GT as address in MAP layer for make sure he will be receiving the MT_FSM for this SRI_SM, this flow is wrong as well, because if the subscriber is ported-out, anti-spam shouldn't handle the message, so how it should be handled usually?