I am using Agenda Fusion as a replacement for the builtin
applications. There is a setting in AF5 to allow it to take over
the 'links' for the builtins. This works great from the Today
page, allowing you to get to Agenda Task & Agenda Calendar
when you click on the upcoming events.

...the problem is with the phone application...

How do I dial a number from Agenda Fusion? The builtin app
allows you to tap on the number and it'll dial. I haven't figured
out a way to do this from AF...

Thanks...

On my Fusion (I am still using 4.X) the contacts allows you to have a split screen with the details in the top window pane. I can tap on the number in the detailed view. This does not work from the summary list in the bottom window pane.