Has anyone had a problem with USSD services consuming too much network resources?
For instance:
- no calls were possible to make in certain locations, or
- the bottom line (financials) has suffered, or
- other services were unavailable.
We have been in USSD business for 5 years, working with tens of millions of subscribers and never had problems. What is your experience?
Clarification added August 19, 2008:
To be specific:
How many USSD Phase 2 sessions from one location are needed on average to take the network down?
Are there any data about USSD loads and network performance (factual data)?
Clarification added October 20, 2008:
I have found one instance recently. An operator decided to send open USSD Phase 1 balance notifications which would close when a user cancels them. They hang open for a minute. Very soon three regions could not make calls.
Morale? Don't do that!
Answers (5)
USSD works very well and does not cause any network problems. It is the most efficient way to communicate commands for any purpose in GSM
Our stint with USSD has been for over 6 years now and I think the problem that you have mentioned could be because of the following :
a) Congestion in the SDCCH channel which could result in failed calls even since the channel in case of USSD is same as used for voice and in case of sms , its a totally different and dedicated channel.
b) pls check the dimensioning of the USSD gateway and also the browser application load balancing/throttling capabilities
We have developed USSD solutions over many years and now even developed solutions for various VAS services and even enterprise apps and with the right dimensioning of the network nodes, it will never give you a problem. Thanks
There is indeed a theoretical risk that voice calls are affected by high load on USSD. However, all depends on 2 elements: 1) The amount of subscribers and 2) The way the USSD service is set-up.
For the first point, the reason is logical: the more users you have on USSD, the more likely that there might be congestion in the SDCCH channel.
The second point, the way the service is set up, is perhaps less evident. USSD is used for different purposes. In one of my previous jobs, we set up 2 main services with USSD: a) Prepaid status check and b) info SMS portal.
a) Prepaid status check: a USSD access code is entered by the user and he gets as answer the result by USSD message or SMS. The USSD 'session' is immediately ended then. This type of services cause very little impact on the network (a bit comparable to SMS as load).
b) info SMS portal: The user enters a USSD access code, and gets as answer a USSD message with different menu option (e.g. 1. Weather, 2. Horoscope, etc). He answers to the USSD message with just a number. A whole 'menu structure' is set-up in this way to cover the SMS services. At the moment of the last menu choice, the user gets info on the tariif and then gets a premium SMS with the info. With this set-up, the USSD session remains open much longer, untill the user has accessed the last menu item. This approach puts more load on the network and USSD gateway.
Menu browsing over USSD session requires extra resources especially SDCCH and SS7
This will be solved by adopting dynamic SDCCH dimensioning and fixing session Timeout
The Core Network has to support the functionality of receiving calls during USSD session
Mauro G.
Telecom. Engineer, MBA. Former CEO Micropagos (Mobile Payment) and CCO Inswitch Solutions (Telecom Solutions).
We have deployed several USSD GW in many mobile operators and we have never encountered, so far, any network problems. Of course, you should properly dimension the amount of users accessing the service and properly time the USSD session
