How to make a USSD call on a iPhone from a button in a webpage?

Question

How to make a USSD call on a iPhone from a button in a webpage?

I have tried the urlencode tel%3A*141%23 but that still does not work.

This is possible cause I can do a USSD call from my contacts application on Iphone?

Does anyone have a solution for this, I don't even need the USSD call to run in the background, just to make the USSD call.

I have read https://developer.apple.com/library/ios/#featuredarticles/iPhoneURLScheme_Reference/Articles/PhoneLinks.html about the special characters * and #

But how does my Contacts app do it?

Answer 1

The contacts app has special privileges us mere mortal developers cannot possess.

The * and # characters are blocked from being used in tel: URLs.