We recently ran into the following issue with native defaulting of fields on the New Phone Call form from an Activities sub-grid in CRM 2013. The functionality exists in CRM 2011 and exists in CRM 2013 if you create a New Phone Call from a related Activities grid.
Then if you click to add a new Phone Call, a new Phone Call record displays with the Call To and the Phone Number field automatically populated.
This is a great time saver and allows you to quickly create a Phone Call record. The issue is if you use a sub-grid for Activities (rather than needing to navigate to the related grid) then the Call To and Phone Number won’t auto-populate as it does from the related grid or how CRM 2011 used to default it.
For example, I have an Activities sub-grid on my Contact form which allows me to easily create a new Phone Call directly from the sub-grid.
This pops open a new Phone Call record but without Call To and Phone Number populated.
Microsoft was made aware and a Connect item has been created here. Any upvotes will help bring this functionality sooner rather than later!