I'm running the latest 8/11 Standard. If I go to the People Tab and have a contact with a mobile number and a work number...I can hit the mobile icon and Tachi opens and dials the mobile. If I hit work...it dials the work number. Text...opens texting. Clicking on the contact picture brings up their contact card. I can do everything from there too.

If I go into "All People"...same deal, it calls whatever number I select for the contact if there are multiple entries.

I haven't applied any fixes, since I'm pretty sure it was cooked into this version.