Basically, if something can be sent to a collections agency (in this case the internal Verizon collections agency), the it is a DEBT and thus the creditor (VerizonWireless) CANNOT refuse payment.
To clarify, payment with Federal Reserve Notes cannot be refused, else things will not go well for them in court.
Is it legal for a business in the United States to refuse cash as a form of payment? Section 31 U.S.C. 5103, entitled "Legal tender," states: "United States coins and currency [including Federal reserve notes and circulating notes of Federal reserve banks and national banks] are legal tender for all debts, public charges, taxes, and dues." This statute means that all United States money as identified above is a valid and legal offer of payment for debts when tendered to a creditor. There is, however, no Federal statute mandating that a private business, a person, or an organization must accept currency or coins as payment for goods or services. Private businesses are free to develop their own policies on whether to accept cash unless there is a state law which says otherwise.
Basically, if something can be sent to a collections agency (in this case the internal Verizon collections agency), the it is a DEBT and thus the creditor (VerizonWireless) CANNOT refuse payment. Since payment of a Verizon bill is frequently after some or all of the service has been given, their is debt (money owed for services previous rendered). Retail is different because there is no debt owed to the retailer since the merchandise ownership is only exchanges (barring a contract) after the payment has been given. (technically, it could be argued in some cases that a verbal contract has been established and thus a debt has been agreed to).