When an Mpesa Paybill number is in Frozen State then it means that it has been suspended by Safaricom.
If you are making a payment to a government organization and are getting the error messages "Failed. M-PESA cannot complete this operation. The paybill number charge debit party in the frozen state which does not support current service", then it means that paybill number is not anymore supported.
The president recently asked all government organizations to shut down their paybill numbers and use mpesa paybill number 222222.