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In a billing system each customer has their own account. In many systems the account may be further subdivided, often into "sites" which will either receive their own independent bill or will be grouped together into one or more combined bills. Billing systems have many different ways of controlling and arranging these relationships.

Tariff/Rate Card

A set of rates that can be applied to a customer. Often this tariff is for a specific set of services (such as calls, data, fixed line services, etc). This tariff is normally given a name, and this name will often relate to the product that the customer has been sold.

Rate/Tariff Value

A price for a type of service or usage event. E.g. 5p per minute for calls to UK National numbers, with a 2p minimum charge or £10 per month for line rental. Each rate will normally have a start and an optional end date so that prices for the same item can be varied over time.


The process of taking usage data (and sometimes also recurring charge information) and calculating the price for each item based on the duration or quantity and the billing configuration for the customer that the item is to be billed to. The rating engine will take rates from the tariffs and apply any special rules and discounts that may be applicable (including bundles, volume discounts, etc).

Bundles/Packages/Included Minutes

A bundle is a special form of discount package that normally applies up to a specific limit of usage. These bundles typically relate to amounts of call minutes or airtime, numbers of text messages or volume of data that a customer can use for free (or as part of the plan that they are paying for).

In some billing systems a bundle can be applied to a tariff so that it is automatically applied to customers with that tariff and in some systems can also be triggered by a service or product that the customer is paying for. In other billing systems, a bundle must be manually applied to the customer or CLI/MPN/line that it applies to.


Fraud is a term that encompasses a number of different things, but in all cases it is usage that is attached to a service that the customer has not authorised or is unaware of.

In some cases a scammer will direct a customer to phone a premium rate number to ring up large bills that the scammer will receive a payment for. In other cases someone will gain unauthorised access to a telephone system and use it to make expensive calls to international/long distance or premium rate numbers (this is often referred to as Toll Fraud).

VOIP (Voice Over IP)

Routing voice calls as packets on a network rather than analogue signals on a copper wire. This network can either be a private network or the public internet. See also SIP Trunking.

SIP Trunking

SIP Trunking is reserved VOIP capacity that a user can utilise to make telephone calls from their phone system without having to have dedicated lines installed (e.g. ISDN2/30). A SIP Trunk provider will normally allow a user to make a specific number of simultaneous calls through their VOIP platform, but will often allow the user to increase or decrease their capacity commitment at short notice (something which is not possible with physical lines).

Charge Code/Charge Group/Charge Band

An identifier for a destination or type of usage, such as Local Call, Call to France, SMS, Roamed Data, etc. This code typically groups together several underlying possible dialled numbers (e.g. a call to a Vodafone mobile will include 07436, 07437 and hundreds of others) or class codes (dictated by the carrier or supplier).

Dialling Code/Dialled Number/Dialled Digits/Dial String

The telephone number that has been dialled by a customer. This may sometimes not be a real telephone number but instead be a service name or description. This will normally be adjusted by the billing system to conform to a standard format (e.g. stripping off international prefixes such as +44, adding or removing leading zeroes as required, etc).

Class Codes/Call Classes

Service codes provided by the carrier or supplier. They usually look like charge groups, but will sometimes contain more detail than is required for billing. In a number of cases they are mapped 1 to 1 with a charge group in the billing system.

CDR (Call Detail Records)

Data from the supplier or carrier (often in the form of CSV files delivered via FTP) that details usage events by a reseller's customers. These records will normally include calls, text messages and data events (as appropriate) and will include the source of the call, the destination, the time and date, the duration and any additional information that the supplier deems relevant.

CLI/MPN (Calling Line Identifier/Mobile Phone Number)

Usage information in a telephone billing system is normally associated with a CLI or MPN. Traditionally and strictly the CLI refers to the telephone number making a telephone call, but this term is often also used to refer to the destination number for inbound numbers. A billing system will store associations between CLIs/MPNs and customers in order to bill usage/calls to the correct customer.


A service is a product sold to a customer that is normally billed at a fixed rate not related to the amount of usage. Examples include line rentals, inclusive minute bundles, broadband rentals and installation charges. These charges are often billed monthly and a billing system will normally support billing them in advance. Service charges normally get added to the billing system in arrears by importing or reconciling supplier bills or automatically when a supplier order completes.

Traffic/Usage Data

The term "traffic" is sometimes used to refer to the call data (or other usage data) that is held by the billing system - this is often referred to as "call traffic".


Roaming is in effect when a user of a mobile plan uses their device (mobile phone, tablet or other device connected to a mobile network) on any network other than the one they buy their service from. In most (but not all) cases this is a network in another country that the user is visiting. Roamed usage is often charged or processed differently from that on a user's home network and may be subject to additional usage limits.

DRC VAT (Domestic Reverse Charge VAT)

VAT regulation changes that came into effect on 1st July 2016 require telecoms suppliers that provide services for resale to not charge VAT on them (if the reseller purchasing the services is VAT registered), but instead report the services as being "Subject to Domestic Reverse Charge VAT" along with the amount of VAT that would have been charged. The reseller purchasing from these suppliers must then account for the VAT themselves and pay (or offset) the VAT directly to HMRC. These regulation changes only apply to speech services (e.g. calls and SMS/MMS messages) and do not apply to data services or line rental charges.

NGCS (Non-geographic calling services)

In July 2015 new rules came into effect in relation to charging for calls to non geographic numbers (e.g. 08, 09 and 118 numbers). Instead of each provider deciding their own rates for calls to these numbers, the charges would be split into 2 parts - the access charge, which would be decided by the end customer's supplier and which must be the same for all calls to NGN numbers from a customer's line and a service charge that would be determined by the NGN provider and would be the same regardless of the service provider used by the end customer.

This enables business using NGN numbers to state with confidence how much a call will cost a customer and for the customer to have a better idea of the actual cost of the service they are using. These rules only apply to calls made from consumer phone services and not to business customers, however most suppliers have applied these new pricing rules to business customers as well as consumers.

NGN (Non-geographic number)

A non geographic number (NGN) is any telephone number that is not tied to a specific geographical location. Numbers starting 01 and 02 numbers are geographical and all other UK prefixes are technically non geographic. In practice, NGN normally refers to inbound numbers starting with 03, 08 and 09 that often have charges (e.g. for freephone numbers) or revenue share arrangements (e.g. for premium rate numbers) for receiving inbound calls.


SIM refers to the SIM card that is used in a phone to identify the user's identity to the network. SIM stands for "Subscriber Identity Module" and each SIM card has a unique identifier and stores encryption keys unique to that user. Sometimes the term "SIM" is used informally to refer to a mobile connection itself rather than the SIM card (e.g. "that SIM made a call...").

Supplier Bill Reconciliation

The process of loading in a bill from a supplier and comparing or reconciling it to data in the billing system. This is done to ensure that all services a supplier is charging for are being billed on to an end customer (to determine the margin and prevent revenue leakage) and to ensure that any services that a supplier has stopped billing for are ceased in the billing platform. Running reconciliation regularly is important to ensure that the billing system is kept accurate and up to date and for revenue assurance purposes.

CDR Importing/Loading/Reading/Mediation

Suppliers provide call data in a wide variety of formats and it is the job of a CDR importer or loader to read in this information and convert it to a common format that the billing system can understand. All CDRs will normally have a source number or identifier, a destination number, a call date and time and a duration, but many will have additional details that affect how the call is to be processed. The CDR importer will standardise leading zeros and international dial code formats, and in some cases may have to combine records from the supplier into a single entry or split a single entry from the supplier into multiple records (perhaps so 2 legs of a call can be charged separately).


Provisioning is the process of ordering a service from a supplier and configuring that service for use by an end customer. This provisioning activity may be automated by using APIs or some other computer to computer interface provided by the supplier, or may be performed manually by users on a web portal (or similar).

Virtual Reseller

A virtual reseller is like a normal reseller, however they typically only buy services from a single supplier that offers an integrated billing solution. The reseller is free to set their own rates for services that are being sold to end customers, but those services are all provisioned and billed by the suppliers systems (rather than the reseller's own).

WLR/WLR3 (Wholesale Line Rental)

Wholesale Line Rental allows resellers to purchase lines from Openreach/BT at wholesale prices and sell these onto their own customers. WLR3 covers PSTN, ISDN2 and ISDN30 products, but Openreach also provide other wholesale products outside of WLR (e.g. broadband).

Anything else?

We add to this list all the time, so send us an email and let us know what we've missed.

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