Data Marketing

OSIS, the origin

Copywriter: Lee Bratton, Account Manager, YouCom Direct


Have you ever seen your business listed on a directory site and wondered how it got there? Perhaps the information is wrong and you correct it but it reverts back to the incorrect data again? It will help if you understand the origin of that information. The national database known as OSIS.    

In this article, YouCom Direct will share;

– What is OSIS?
– Why you can’t change your business details on the directory site displaying the wrong data.
– How you can change your business details on OSIS.
– How do you find OSIS?
– European OSIS
– Alternative databases.

As a directory agency we manage a company’s details for their stores across all print and online directories. It is our knowledge together with buying power that makes us a valuable partner. But we don’t just keep our knowledge to ourselves. OSIS is not widely known but equally it’s no secret either.  

What is OSIS?

“OSIS” stands for Operator Services Information System and is a stream of seemingly endless data flowing along corridors of database servers.


Like all large datasets, OSIS is much in demand and has never lost its popularity. It is a database of directory data managed by BT Wholesale Directory Services. The data is used to populate the BT Phone Book printed directory and is bought by other companies such as Thomson Local, Yellow Pages (once owned by BT), the 118 telephone directory companies and a large amount of online directory sites.   

YouDirectories-OSIS-the-origin-of-directories-4       YouDirectories-OSIS-the-origin-of-directories-Yalwa  

Directory sites like are very well established, has 10.9 million monthly views, but how did they begin? Look at, see how different they are to Yalwa currently have 82,000 monthly views (a far cry from 10.9 million), yet they already seem to have a lot of businesses listed on their site.  

This means when your customers search for your business, one of the Google search results could show a Yalwa URL link. But the information could be incorrect. Perhaps your telephone number is wrong on Yalwa, or the address inaccurate.

So how did they obtain their data and your business details specifically?  

BT Wholesale is obliged to make OSIS available to any organisation who wishes to pay for it, specifically under Universal Service Condition 7.4 (USC7.4) which states that

“BT shall supply [the contents of a directory information database] on terms which are fair, objective, cost-oriented and not unduly 
discriminatory…”. A condition frequently challenged by those who pay to rent it. 


The OSIS database contains more than 26 million residential and business names, addresses, and telephone numbers supplied to BT by over 80 UK Communication Providers and sources such as Companies House.  

When an individual requests a new telephone line and agrees to be listed in the telephone directory, the data will be entered into BT OSIS. When a new business starts up, the data will be entered into BT OSIS. This makes the BT OSIS database very accurate and up-to-date (The database is updated 6 days a week).    

There are three types of entry on the OSIS database:

Directory Entry – The printed phone book is comprised of these records. A telephone number can be appended to a name and address that matches to a directory entry record on OSIS.

Directory Enquiries Only – These listings are not present in the phone book, but are made available to directory enquiry 118 services. You can append a phone number from these entries where it matches the name and address on your record.

Ex-Directory – Ex-Directory listings are only available in telephone directory enquiry 118 services. Don’t worry, only the fact that the record is ex-directory may be provided.


Why can’t you change your business details on the directory site displaying the wrong data?

Type your business brand name and the town of your store location into a search engine like Google. If you see an incorrectly listed entry for your business on an online directory like Yalwa, why can’t you contact them and change it?  

The short answer is, you can. You can also pay them for a paid-listing to feature more prominently in their search results (the fundamental service of YouCom Direct as an agency). But the next time that online directory uploads a new data feed from OSIS, all the non-paid for listings will be replaced by the OSIS data. In other words, although you’ve changed the incorrect data, the change is overwritten by the old incorrect data from OSIS.

You can’t stop the waves and you can’t surf against the tide either…    


How can you change your business details on OSIS?

Keeping it simple, there are two options.

One, contact BT Wholesale and make a formal request to amend the data. This process can take between three to six months. You will need to check it afterwards to ensure there isn’t a duplicate data entry still containing the old incorrect data.  

Secondly, you can take the stance of the larger advertisers and pay a specialist directory agency like YouCom Direct to do it for you. YouCom Direct will reach out to BT OSIS and change your data as quickly as 1-2 weeks. We see it in all walks of life that businesses respond quicker, to other companies whom they sell to (in our case, BT sells directory advertising to us for paid listings and paid classified adverts).  


How do you find OSIS?

You don’t find OSIS.  OSIS finds you. 

But you can change their data.

BT Wholesale Directory Solutions (BTWDS) is a ring-fenced unit within BT Wholesale. They aggregate telephone number information from Communication Providers (CPs) in order to produce an accurate central telephone number database historically referred to as the OSIS database. Under OFCOM regulations, all UK CPs that have signed a Schedule 11 agreement have to provide BTWDS with their customers’ name, address and telephone number information. At present there are over 80 CPs in the UK e.g. BT, Virgin Media, Cable & Wireless etc.  

OSIS data can only be used in Directory Products and Services by companies who wish to produce Directory Information products or services, who agree to their pricing terms and gains authorisation from BTWDS to receive OSIS data. OSIS data is sold under specific terms and conditions including the Data Protection Act 1998 and the Information Commissioners Code of Practice on Telecommunications Directory Information covering the Fair Processing of Personal Data and Electronic Communications Regulations 2003. – Licensees must agree to abide by these within the terms of the Directory Information Licence Agreement. OSIS cannot be used for Validation and Verification of individuals or in associated Validation and Verification Services.    


European OSIS

Operator Services Information Systems aren’t only peculiar to the UK of course. YouCom Direct talk with media owners across Europe and manage listings in several EU countries. In Sweden these are primarily Eniro and Rejta businesss directory websites, Din Del and the 118 118 directory assistance service. In Norway, Proff and the 1880 directory assistance are the main directories. Danish search services are marketed under the (now owned by Eniro), Mostrup and Den Røde Lokalbog brands plus several others, while Panorama Firm is the brand in Poland. Finland customers encounter the 0100100 brand.

All take their data from OSIS equivalents such as Factual, a database of 75.8 million local business listings in 50 countries. Or Schober, a B2B data provider in Germany.    

Alternative databases

There are other data sources also, OSIS shouldn’t be the only place you look.  

The Postcode Address File

(PAF) is a database of every address in the UK to which mail is delivered, together with its appropriate postcode. This database contains over 28 million addresses of residential, business and other organisations. The PAF is produced by the Royal Mail and is updated quarterly.

The National Change of Address register
(NCOA) records individuals and businesses when they relocate. CRM practices teach all marketing mangers that to retain existing customers is often more cost-effective than acquiring new ones. With the NCOA register you can maintain contact with your customers when they move home, saving cost and increasing profits via an elongated customer life cycle.

The Gone Away Suppression
(GAS) File from The Data Agency uses both public and private data sources and is a compiled list of individuals at addresses they are known to have moved from. In every case, each move out is qualified by a move in to ensure accuracy.

Despite the other data sources, OSIS is certainly the most powerful database storing data on your business and if you don’t ensure its correct (and remains correct…), then every other organisation and directory site renting their data, will broadcast incorrect details about your brand and ruin your SEO.

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OSIS – Operator Services Information System

GAS – Gone Away Suppression

NCOA – National Change of Address register

PAF – Postcode Address File

B2B – Business to Business

YALWA – Yet another local web application

CP – Communication Providers

SEO – Search engine optimisation

BTWDS – BT Wholesale Directory Solutions

Data source:

OSIS Definition

BT Wholesale

Universal Service Condition explained within an Ofcom dispute raised by Thomson Local over costs of renting OSIS.

Ofcom dispute on OSIS rental costs between The Number (118 188) and BT wholesale proving that telephone directories like 118 118 also obtain their business data from OSIS

EU Factual Database

Schober Database

Required reference

YouCom Direct News Article, Jul 2019, London, ‘OSIS, the origin’.



Lee Bratton