GroupWise uses the old TAPI or Windows Phone Provider which is far from what Jabber, Skype4Business, etc. use.
In the background the links are HTML and use the TEL:xxxx format, but there is a special handler in GroupWise that kicks them off to the old TAPI... add an other setting like "ClickToCall Links" and let the OS handle the TEL:xxx or SIP:xxx links - then dialing from GroupWise to a softphone already works.
I found a hack to change it in the details, but not for the QuickInfo - showed it to some users and first question was: Why doesn't it work in QuickInfo :/
Don't think it is hard to implement and would releave a bit of pain with regards to 'integration' to softphone based phone systems (aka all new ones)