- This topic has 10 replies, 1 voice, and was last updated 16 years, 11 months ago by A.
25th May 2004 at 09:10 #38225RiteshGuest
Can anyone give an outline of how local direct calling(dialling) works for an international inbound roamer?
For example a subscriber roams into a VPLMN, then how an the VPLMN service provider gives the local direct dial service to the subscriber? I mean is there some extra messaging between the HPLMN and the VPLMN? Or otherwise what is the conceopt behind its implementation.
Ritesh25th May 2004 at 09:19 #38226RoameoGuest
The MSC/GMSC is configured to fire the SRI(routing info) first to some configured SCP in the VPLMN which would have the list of roamers and their current location. The SCP which acts as a dummy HLR would then fire a PRN query to the VLR if he exists within the roamed network.
If not the SRI-ACK is returned with the MSISDN and the IAM moves forward to the CDPA GMSC.
R….25th May 2004 at 09:32 #38227RoameoGuest
Alternatively, instead of maintaining a Database of all roamers we could also have the MSC fire an SRI to the CDPA HLR, and if the SRI-ACK contains a MSRN number belonging to the visited network the CDPA in the IAM can be replaced with this MSRN and the call can be routed within the network.
R….25th May 2004 at 16:21 #38228Jack SparrowGuest
Can you explain a Bit slowly ?
1.A Party in MSC-A Calls B which Belongs to Another Country and presently roams in MSC-A.
2.How the call starts as ISUP or MAP Query…
Rgds25th May 2004 at 16:40 #38229RoameoGuest
Call Starts as an Isup Message and it lands up in GMSC of A-party.
Now GMSC of A can be configured to fire SRI(if possible) to the B partys HLR which returns back with the MSRN. GMSC of A can validate if this MSRN belongs to a local range and decide if the call can be routed locally.
This approach depends on whether B partys HLR recognises a SRI query coming from a foreign GMSC.
Rgds25th May 2004 at 16:48 #38230Jack SparrowGuest
This is AIRTEL’s Local Rerouting.
What happens If the MSRN Comes Differently – Somehow B Gone to another Network ?
Then what about billing how you can relate the call goes from GMSC-A to B-Party ?
Rgds25th May 2004 at 16:59 #38231RoameoGuest
If the number comes differently just send the IAM as is.
I did not get the billing point. Could you elaborate?
Rgds25th May 2004 at 17:19 #38232Jack SparrowGuest
A-Party in Delhi AIRTEL
B-Party in Delhi BSNL
Lets Say the B-Party gone to London from India.A-prty calls B and AIRTEL GMSC is getting UK-MSRN.
Who will pay this Bill ?
A-Party who just made a Local Call from ?
A-Party Network ?
B-Party wont accept if you ask him to pay this Bill.
This is where the Billing Isssue Comes Up.
Rgds25th May 2004 at 17:32 #38233RoameoGuest
I agree with your point. But if you just route the IAM as it is(if its a non-local MSRN) wont it work? The negative point is there will be multiple SRI’s.
If this wont work the first approach where-in you have a Database(SCP) which has the list of active roamers + the VLR addresses (by tapping the roaming links) should make it more trendy? In this approach the MSC fires a SRI to the SCP, if the SCP returns with a valid local MSRN, then call is routed locally else it just gets fwded.
What do u feel?
rgds25th May 2004 at 20:16 #38234Jack SparrowGuest
Hi …Technically routing any MSRN is not a Problem.As I said if the MSRN is coming for a UK Network Who will pay it ( A-Party,A-Operator,B-Party,B-Operator)& How you will make him pay it ?
If you say A-Party / A-Operator, then sorry impossible.
B-Operaor /B-Party-Need Billing Info.
How you will generate Billing which has both the A & B Party Call Reference.
Make the routing as 1.Local SCP Kind DB no Result go to next Routing as Normal that is also fine to Do.
But the only point where I am not satisfied is Billing the MSRN Leg.
A Good news to you.There is a solution from TANLA SOLUTIONS-Indian Company.
But still I am concernd abt HOW DO THEY GENERATE RELATED CDRs ?
Rgds26th May 2004 at 04:28 #38235AGuest
As per my understanding party A should get billed incase the call is routed internally in the VPLMN of Called party(HPLMN of calling party). This is so because the call will be treated as a local call.
Roameo, referring to the solution of a dummy HLR in VPLMN, the problem is the IMSI. HLR has to send IMSI in PRN. However in the VPLMN, the IMSI is stored only in the current MSC/VLR. The dummy HLR or even the actual HLR of the VPLMN doesnt have the IMSI of the inbound roamer and since IMSI is a mandatory parameter of PRN, I dont see how the dummy HLR can send it.
As for the alternate solution of obtaining the MSRN from HPLMN and then routing the call internally, wouldn’t that require code changes in the MSC? On the contrary the first solution may be achieved by modifying the routing tables of MSC (ofcourse a new dummy HLR would have to be added).
Do correct me if I am wrong.