Technical Note on control of International Short message Service.
Author: Abraham Paul email@example.com
1. Current problem related to Inter Network SMS call handling.
There are frequent complaints of receiving obnoxious SMS from other networks. The problem faced is that at present GSM Short Message Service does not follow separate numbering plan and therefore, uses same MSISDN. Because of this, it is not possible to easily discriminate the signals concerning to VOICE Call and SMS in the Gateway Switches. Therefore, it becomes difficult to selectively block international SMS. Blockade of inter-network transactions of SMS enblock will be a retrograde process. Therefore, there is a need to develop new methods to over come this problem.
2. Voice, FAX and DATA service in PLMN use different MSISDN. It is expected that future numbering will contain the identity of the type of service to be handled along with the identity of the service provider and the type of carrier etc. Same idea can be adopted in the case of SMS also.
3. Different Long-term solutions: –
a) Discrete routing of signaling path belonging to SMS.
Additional routing tables and programs are to be realized in the GMSC to identify signaling Messages belonging to SMS so that it is possible to reroute these to different transit routes e.g. to an exclusive SM SC, without invoking HLR interrogation by GMSC, but shall be done in different GMSC.
b) Allocation of Separate Number range for SMS and SM SC.
Service provider can have understanding with other countries to route in signals belonging to this number range in a separate signaling link.
If this is not possible, Service provider can do number analysis and route signals belonging to SMS messages from other countries in the GMSCs. It is possible to route these into an exclusive SM SC and can control further transport of messages.
c) Usage of IN system to deal with SMS.
By SCM of MSISDN level SMS can cause an IN trigger and shall be possible to control on its delivery using ‘directed number’ facility etc.
d) Incoming call barring based on Operator Determined Barring and SCI.
It shall be possible to realize additional barring programs to do operator determined barring of SMS (MT) originated from other PLMN. Also it shall be possible to include SMS call barring using SCI. However, realization of additional barring programs will require significant development efforts.
e) Exclusive routing of non-HPLMN SM (MT) by SM SC.
It shall be possible to realize GMTT to enable exclusive forwarding of SMS meant for other PLMN by the SM SC which originally forward the SMS. If this is delivered on an exclusive signaling link to own GMSC it is possible to have control on the routing to GMSCs of other PLMNs.
4. Short term solution for Service Provider.
i) It may be possible to prevent delivery of SM (MT) received through WEB or from other PLMN by defining SMS message related timer in the GMSC out of range. It can be experimented whether by setting one or many of the TCAP timers out of range, a failure condition can be forcefully created.
For example the normal range of TCAP timers is 15 to 30 Seconds. If system accepts the ‘below range’ value of say 1 second then the message transfer is forced to fail and the end result will be non-delivery of SM (MT). Service provider has to ensure that only SM (MT) of other PLMN enter the GMSC.
ii) Juridical Interception can be invoked for the complaining subscriber and try to locate the originating PLMN and SM SC so that individual cases can be taken up and resolved through administrative procedures.
Evolution of methods to deal with different mode of communication is also necessary to go hand-in-hand with convergence of these. This is Important for charging, interception and control of use.
GPRS and above evolutions takes care of de-linking of voice and data path, it is also to be examined whether SMS handling can also be de-linked by means of methods suggested above.