T28P & T38G: Speed Dial delay or pause between DTMF

[yoda72]

Hi all,
I'm using both T28P & T38G phones.
I'm wandering how to add a pause or a delay between two DTMF key when using the Speed Dial feature? Does Yealink phones use a specific key for that?
I saw that other phone use sometimes the "p" or "," character to do that.

I'm trying to set up a speed dial DSS key with a phone number and his extension.
And I need a pause (few seconds will be enough) between the phone number and the extension.

Thanks for your help.
A.