Yes, strictly by written agreement we allow pre-payment for all or part of your agreed contract value.
Once payment has been agreed and received, each subsequent bill will be posted to your account ledger, without payment being taken in the usual fashion.
You can view your account balance at anytime from your my.plan dashboard.
MY ACCOUNT > BILLING & PAYMENTS > INVOICE & PAYMENT HISTORY
Please be aware that over the lifetime of the contract after payment, if additional charges are incurred, your advance payment may not be sufficient to cover the remaining bills or final bill.