IN in GSM

IN offers whole range of new features and services and various vendors support different type of services and perpaid being the most used service. Othe then pre-paid there are other services e.g. Virtula private networks (VPN) free phone, one number , premium calling etc, that are not feasible without using Intelligent Networks. You can get hold of the standards that shall provide you all the call flows and other details.

Hello,
Thanks for your reply.
Basically without IN (which means CAMEL in GSM and INAP in fixed n/w) how we used to support pre-paid calls in visiting network?.

According to what i have understood is in CAMEL we look into the T_CSI Or O_CSI flag and decide on using CAMEL for terminating or originating calls.

( In IN these T_CSI and O_CSI work like trigger points for pre-paid user calls, if i am not wrong). According to me, when first time pre-paid user is detected the “MAP messages which flow between VLR and HLR for getting the user related information) will basically hold these flags. So, VLR maintains these flags!!!!!. Again not sure.

And when GMSC or VMSC decide to apply CAMEL for orig/term call the request (INIT-DP) will be sent to gsmSCF (a process running on HLR) from gsmSSF ( a process running on MSC).

The point to note is, the VMSC’s gsmSSF will interact with (gsmSSF)HLR of the pre-paid user home network. Please correct me if i am not wrong.

And then gsmSCF will reply with Request Reports (ApplyCharging,EventReportBCSM,Connect… etc) and when the call gets disconnected the Reports generated @ VMSC will be reported to HLR, which update the billing system.

How pre-paid was support without CAMEL is still a question?. One possible answer can be VMSC maintains the CDR’s and we collect manually or using X.25 link from VMSC and update these CDR’s on HLR. But the problem is if user makes a call whose cost is more then the present available balance in his/her account then above said will not work.

And i have one more point which requires your support to know better, how does OSS (Operator Specific Services) will be supported using CAMEL?.

I tried to understand this point, and have the following idea. CAMEL supports play-announcement, now to play announcement ( which is specific to an operator), the VMSC can use gsmSRF of per-paid user’s home network.

I mean, the gsmSCF which requests VMSC (gsmSSF) to handle play-announcement will refer gsmSRF of pre-paid’s home network.

But i am not sure. Please clarify my understandings.

-Thanks
Hari

Hello Hari,

* CAMEL is the best solution to support Prepaid Raoming.Or we have to go for proper IN-Data Defintions to co operate with Other PLMNs.That is not possible with all the vendors.

* There are differnt IN Keys,which can be used to Invoke the IN Services.By proper defintions for each triggering you can make differnt setup of call handling for differnt keys.

* HLR Just provides a copy of Subscriber data to VLR.But SSF/MSC is responsible for acting according to the triggering table.

* gsmSCF Runs as differnt Functionality.It is not a integrated functionality of HLR but can be implemented in same HW Platform.it can work as co working application or standalone node.

* gsmSSF always interacts with gsmSCF/SCP while processing a call…not with HLR.Since gsmSSF is implemented in a MSC Node…depending upon the setup the MSC Can Initiate a Authrization process.But it depends upon the MSC Functionality not in SSF.

*During a call the SCP & SSF are always in communication with eachother.So the billing is like ONLINE Billinbg for PREPAID Subscribers.No need to go for POST Processing of CDRs.But MSC includes this call datas in its CDRs.Which can be used or not used for other purposes.Charging will be purely controlled by SCF incase the implementation is for PREPAID.

* PREPAID Roaming is avilable without CAMEL.But in this case the above mentioned CDRs from MSC willl be used.But the charging will take place 5/6 times in a day.And it depends upon the CDR reception from other VPLMNs.Then they will apply OG/IC-Barring if they find somebody without money.

*OSS in CAML-No Idea

*For announcement there should be Close cooperation between SSF & SCF so it is not possible in case of a Country to Country Roaming.

* There are some other methodes like USSD and Call back features…etc….

Hope this clarifies a bit 4 u and Call Flow Traces sorry..I cant get…since there are 16 Links between our SSF and SCF…I cannot do tracing for this.

Our Analyzer-Nethawk is capable of Two Links only.

Rgds

Scot

Scot,
Thanks for your valuable inputs.

The USSD callback solution which you are refering is about home USSD server triggering two calls and cross-connecting both the calls if i am not wrong.

-Thanks
Hari

Hi Guys,

Very informative discussion. Thanks

Does anyone have an idea as to which CAMEL phase (i.e. Phase 1, 2 or 3) is currently implemented within mobile operator’s networks?

Does the fact that an operator has GPRS, have anything to do with what CAMEL phase they are at??

Just going back to the discussion, in terms of CAMEL I think the whole idea is to enable an operator to offer OSS (Operator Specific Services) that are avilable while roaming (of course the visited netwrok needs o be CAMEL aware). This is done by trnasferring the CAMEL Subscription Information (CSI) to the VLR of the VMSC at registration of location update or when CSI changes.
One of things the CSI has is the address of the SCF in the HPLMN and the VMSC can query the SCF in the HPLMN in case it comes accross any armed triggers.

Kind Regards

Andrew

Thanks Hari for the response and the info. Appreciate it.

Hi Hari,

Can you explain a bit about using USSD and connecting two Calls ?

MAP-Process Unstructured SS Request.

Rgds

Sunil