If you are unable to make an outbound local call, make sure your account is up to date and hasn't been blocked for non payment, you can do this by logging into My Account.
If you are trying to make a toll call, you need to have enough credit on your account, if you don't then simply top up via My Account.
If everything is up to date, try using the phone in a different jackpoint, still not working??
Then try using a different phone, you may find your phone needs to be replaced. Still not working?
Then submit an online request or give us a call and we can go through some troubleshooting steps with you and if need be send out a technician to fix the problem.
But remember, if they find the fault is with your equipment or internal wiring there may be a charge on your account.