Roaming Value-Added ServicesBY:Rawand Dlshad Jaf

IREG Engineer

Roaming in GSM Network

International roaming offers a great opportunity for wireless service providers to improve revenues and generate more profits.

They are continuously exploring new ways to attract more roamers to their networks.

As you know the roamer set the hand to network register automatically according to the Signal Strength, Reselection may be happens when the roamer moves and the Roamer don't have the loyally to any network out side home country.

But the question is how we can attract the roamer to manually network selection

The Ans .”by Cost of usage, Service , Discount,…ECT” And VAS

Optimal Routing

What happens when Roamer calling another Roamer in the same Country?

MSC/VLR

HLR

MSC/VLR

1-Dial

B

2-Call route to home network

MSC/VLR

3 6

3-Sending routin Info

6-Provide by MSRN.

4-asking MSRN

5-MSRN

8

Call Route to B

B

A

Country X

Country B

Optimal Routing

This is surly not an efficient routing because is require tow international call legs , for that we need optimal routing (OR) as value add service to attract & retain Roamers in Visit net.

OP allows a call to routed directly from originating MSC to MSC currently serving roamer for that the international call will be avoided saving cost and OP can be applied to following scenarios:

1- Inbound Roamer to Roamer call in same Country and network.

2- Inbound Roamer to Roamer call in same Country but other network.

3-A local Subscriber calling Inbound roamer in same network.

Implementation

• Usually access code is used fallowed by the regular B party international number.

• All the OR call are routed to a special Platform which enable the OR, there could be several different ways to implement OR in the network.

• The three important requirement for any OR implementation are:

1. Acquire, maintain, and manage the data for all inbound roamers currently in the network in real time.

2. Analysis of the B party number to check if it is an inbound roamer currently in a network implementing OR or in any other PLMN within the same country, where the call could be routed locally.

3. If OR is possible, then acquire MSRN from the serving MSC to route the call

locally.

The key roaming procedures, such as location update, insert subscriber data, authentication, and cancel location messages provide all the critical information to build the database for OR purposes (by extract the signaling messages from the CCS7 links carrying MAP traffic to partner networks).

For example, by decod-ing a UL/ISD procedure, the following parameters can be extracted.

■ Subscriber’s IMSI

■ MSISDN

■ HLR address

■ Serving MSC/VLR address

■ Timestamp for first and subsequent UL

How can I get a database for OR?

Typical implementation. (Roamers under Same Operator)

Mobile/inbound RoamerMobile/inbound Roamer

Fixed lineFixed line

OR pattform

OR pattform

1-IAM,B party

number.1-IAM,B party

number.Roamer data

baseRoamer data

base

2-Get IMSI <VLR/MSC>2-Get IMSI

<VLR/MSC>

3-IMSI, VLR/MSC3-IMSI, VLR/MSC

MSCMSC

VLRVLR

4-A

sk th

MS

RN

4-A

sk th

MS

RN

5- R

espo

nse

MS

RN

5- R

espo

nse

MS

RN5-IA

M (M

SRN)

5-IA

M (M

SRN)

B inbound RoamerB inbound Roamer

<OR access code><B party international number><OR access code><B party international number>

Typical implementation. (Roamers in same country but under different Operators)

Mobile/inbound RoamerMobile/inbound Roamer

OR pattform

OR pattform

1-IAM,B party

number.1-IAM,B party

number.

Roamer data base

Roamer data base

2-Get IMSI <VLR/MSC>2-Get IMSI

<VLR/MSC>

3-HLR3-HLR

MSCMSC

VLRVLR

8-IA

M (M

SRN)

8-IA

M (M

SRN)

B inbound RoamerB inbound Roamer

Fixed lineFixed line

HLRHLR

4-SRI (MSISDN)

4-SRI (MSISDN)

5- Ask MSRN5- Ask MSRN

6- MSRN6- MSRN

7- MSRN

7- MSRN Home networkHome network