I'm using Outlook 2013 and Lync on Win7.
I often have to call conference numbers that require dialing a long phone number, followed by a hard pause (an indefinite pause of a certain length is not sufficient, as it's sometimes not enough time), another predefined number followed by "#", another hard pause, followed by a semi-random number, followed by another "#".
On my Android phone, this works perfectly fine, as I enter ";" (semicolon) at each point where I need a hard pause, followed by the number I have to enter.
I was actually able to enter semicolons into an Outlook contact phone number, followed by additional digits, although I was initially confused when after saving, it didn't display those additional characters. However, when I went back into edit mode for the contact, it did display the additional characters, although it appeared to insert a space before each semicolon.
When I tried to call this contact from Lync, it immediately gave me a fast busy, and it didn't even show me what digits it was dialing. I never noticed anything like a prompt for pauses.