NetBilling stores its data in MySQL database, which has the following tables:

• Client
  Describes the client's account with:
  • IP-address and MAC-address of his PC
  • current balance
  • monthly fee
  • traffic discount (monthly fee is not discounted)
  • access flag (enabled/disabled)
  • negative balance permission
  • personal page language
• User
  Describes the users of single client (single IP), who uses PC one after another. Their traffic is accounted in common. Database table contains:
  • personal page password
  • user's first, last and middle names
  • address
  • phone number
  • email
  • daily and monthly reports flags
• Income
  Contains data for all money deposits with clients' accounts, which is date and time of deposit operation and respective sum deposited.
• Outlay
  Contains data for all money charges (except charge for traffic) made to client with their date, time, money amount and charge description..
• Log
  Errors and access warnings from clients' personal pages, their access management operations and payment cards activation stored here.
• Card
  Contains the list of unactivated payment cards. Activated cards are removed from this table. Card's IDs, passwords, values and generation times are stored there.
• Traffic
  This table stores all clients' traffc in traffic zones for each month. Each client has corresponding record in this table for each traffic zone he used. Each month this table will extend with new traffic records for each client. Maximum amount of records in this table can be calculated as M1*Z + M2*Z + M3*Z + . . . + Mn*Z,
  here: Mi - amount of months this client (i) accounted with NetBilling,
  n - amount of users registered by NetBilling,
  Z - amount of traffic zones.
  This table resolves many-to-many relationship between Client and Zone tables.
• Zone
  Describes traffic zones. Amount of record in this table equals to amount of traffic zones defined. Each record contains zone name and description, imbound and outbound traffic price and order index of zone.
• Address
  Contains description of subnetwork addresses in traffic zones.
• Port
  Contains port numbers, corresponding with subnetworks defined in Address table.

Database structure is presented on the following ER-model: