Post Paid: A model of cellular service whereby the customer is charged for usage in the prior month (hence 'post' usage), and hence does not feature any limitations on volume of service used. In contrast, the Prepaid model asks customers to add credit to their accounts prior to usage and their usage is limited to the amount that is added to the account.

Depending on the country of usage, there might be a number of types of charges associated with such service:
-Line Rent or Fixed charges which are basically fees charged by the service provider for the privilege of maintaining a phone number and account with them.
-VAT/Taxes/Govt Fees which vary depending on the country but could add up to a substantial portion of the bill
-Usage charges per minute of voice service, per text/pic/multimedia message sent or received and per megabyte of data service used. Recently this is being replaced by a flat fee for Unlimited Voice, Messaging and Data services.

Postpaid compared to prepaid:
- Prepaid is activated by purchasing credit load vs. Postpaid where you can continue use without the restriction and/or limitation based on the available credit.

Prerequisites:
Postpaid service typically requires two essential components in order to make the 'post-usage' model viable:
1. Credit history/Contractual commitment: This is the basis on which the service provider is able to trust the customer with paying their bill when its due and to have legal resource in case of non-payment
2. Service Tenure: Most postpaid providers require customers to sign long term (1-3 year) contracts committing to use of the service. Failure to complete the term would make the customer liable for Early Terminiation Fees (ETF).

The United States is an example of a country dominated by Postpaid providers (AT&T, Verizon, Sprint and T-mobile) although a smaller market has been captured by prepaid providers such as Boost, Virgin Mobile, MetroPCS, Cricket, Tracfone and Jump