USSD Gateway

USSD gateway stands for Unstructured Supplementary Service Data Gateway which is simply a router, which routes USSD messages from the signaling network to service applications and back. It's also identified as a signalling node which has it's own internal point code as well as own global title.

USSD is a session based protocol used by GSM cellular telephones to communicate with the service provider's computers

USSD uses Signaling channels to transmit bi-directional data between the mobile and the application defined by the operator

USSD messages are used for many things such as

• Notifying
• WAP browsing
• Providing menus
• Activating a mobile service
• Configuring a subscriber quickly and directly
• Location based content services

The network architecture of the USSD Gateway is as follows

There are many advanages of USSD services when compared to the sibling service SMS

• Innovative solution - Menu based
• Immediate push and pull service
• Ease of use for the subscriber
• Easy to validate to the operator
• Longer message length then SMS
• Easy extension possibility
• Can be used by 99.99% of the mobiles which exist for today
• Does not require any modifications to the SIM

In USSD services there are short cuts as well. Rather than accessing a service using for an exampe *500#, and then browsing through the menu, someone may be able to access the ultimate service intended to use directly by, *500*3*2*86568855487*9700*123#. This is another advantage of USSD services where a knowledged user would be capable of performing the task faster.

For USSD implementations, there are two ways possible. That is via SS7 technology or using Sigtran. The pros and cons differ in each case

SS7

Advantages:

• The bandwidth is guaranteed ensuring optimal quality of service
• All operator equipment is reputed to be MTP (standard) compatible

Disadvantages:

• The platform must be hosted near the operator's equipment (STP or HLR)
• SS7 cards expensive to buy
• The bandwidth is limited to a few dozen COC of 64Kb/s

Sigtran

Advantages

• Flexibility and the possibility of having the Gateway away from the operator's site, directly with the Service Provider via a secure VPN network.
• No costly cards
• The platform can be hosted on a site far from the operator's equipment
• The bandwidth is no longer limited but can reach hundreds of Mbit/s
• Items may be connected in stars and not point to point, allowing direct virtual connection and eliminating certain limitations of network items.
• A multinational operator may see their various national networks as a large scale intranet and pool their network equipment.
• The redundancy of the equipment is transparent, several pieces of equipment may have the same address and share the load invisibly for the transmitter.
• Just one SCTP packet can contain several messages ? less routing cost

Disadvantages

• The bandwidth is not as guaranteed
• All equipment is not yet compatible with Sigtran
• Troubleshooting is more complex - IP path and by the number of messages in a frame