There's a way to dial directly from your contacts via a calling card.
Originally Posted by tok
1) In your Google Voice settings, make sure that "Voicemail access" is set to "Yes" with "PIN not required".
2) Install the attached CAB and restart your phone.
3) In your Programs, run CallingCard, and select Menu > Add
4) Fill out as below:
Name: Google Voice
Access#: 1112223333p2 (where 1112223333 is your 10-digit Google Voice number)
Set Insert to "None"
Pin#: # (just the "pound" sign, nothing else)
Set Insert to "None"
Leave Intl. Access # blank
Dial Sequence: Set to "Phone# + Pin"
5) Click Save, select the newly created "Google Voice", and "Activate". That's it!
Now whenever you want to call using your Google Voice number, just browse to your contacts, tap and hold your contact, and select the CallingCard option.