A flaw in Unicom SP text messages

We encountered a problem when using SGIP to develop the unicom sp text message. When we send a marketing text message, the user not only receives this text message, but also receives an additional text message, the content is probably about who sent this text message and what is the billing method.

Originally, our sp messages were free of charge, but users were confused as soon as they saw the "Tariff". As a result, we were complained.

Contact the China Unicom SP technical support to find the reason for N days, and finally get a reply. The text message contains a linkid, so an additional message will be sent.

But we did not set this linkid!

We tried to change every parameter of the SGIP protocol, but this problem could not be solved.ProgramCodeProblem, we estimate.

Then, if we try to send other normal text messages, we will not receive the additional fee reminder text message. Does it seem that China Unicom has this special handling for marketing text messages?

Report to the business department and ask the business department to negotiate with China Unicom for a while.

Finally, I returned to the SP technical reply. The text message contains a linkid. This linkid is not set in our program. Is it in our text message content?

Return to our marketing text message. There is a website in it. Will this website be regarded as a linkid?

After some tests, it was found that it was related to the website. It would be normal if this website was not included.

We continue to test and switch the website address to another one. It's okay!

Then, we continue to study the website and find that the URL has a parameter id = ***** at the end *****

Will this parameter be identified as a linkid? After testing, this is indeed the problem. It is normal to remove the ID segment!

The problem is not over yet. We cannot include such an ID parameter in our marketing SMS. What should we do?

We try again to replace the ID with uppercase, id = *****, and then test again, it's okay!

It seems that the text message cannot contain lower-case id = *** characters and will be identified as a linkid as the user's On-Demand sp sms, so there will be an additional fee SMS notification to the customer.

China Unicom of the potholes extracts commands directly from the text message content (but there may be no other way, the initial design of Short Messages does not consider maintaining the session information between multiple interactions ).

I don't know how many such commands are available in this SP text message. Maybe it can be injected!