You should be able to make calls and send texts without any special setup if the phone is unlocked. Where did you get it unlocked? If through Virgin, did you just pay or did you enter the unlocking code yourself (a lot of people think that once you pay your carrier that the unlock happens automatically - you have to enter another carrier's SIM card and then you're prompted to enter the unlocking code).
If you've done that and your SIM is active on your account, you may have a defective SIM. If that's the case, I suggest calling customer service from another phone to sort this out: