How to add a pause to the tel: uri scheme

I'm aware that to tell the dialer to pause you add a comma to the dial string but if I pass one via the tel: url it simply ignores the comma and everything after it when clicking the link (android 4.5). I tried using P but that gets turned into a 7. Is there anything else I can try?

Thanks

Solution

It turns out that you can't do this with html links. It is possible if you're building a native app but not by invoking the dialler, you'll have to initiate the call yourself.