Historically no one authority was responsible for collating all telephone numbers within the UK. BT was the main source of telephone number information, but their data did not include all telephone numbers from other telecommunication companies.

In 1999 an independent body called The Directory Solutions Unit was formed to collate telephone number information from nearly all UK Telecom's Providers.

BT Wholesale is now responsible for collating all changes to UK Telephone Numbers and the database which the numbers are held in is called BT OSIS. OSIS stands for the 'Operator Services Information System'.

Licensed bureaux such as ADMAR are permitted to hold a copy of the database on-site, thus having instant and unlimited access to every available UK phone number.

We are also licensed to access the Ex-Directory section of the database, but are only able to view names and addresses and not actual XD Phone Numbers.

There is also a third category called DQR which many subscribers are unaware of.

When asking companies to append numbers from OSIS you should note that some telephone numbers for companies with paid full page adverts are missing from the OSIS Database.

The service is funded by licence holders paying a Royalty fee for each search.

A daily file is issued by OSIS containing between 20,000 - 100,000 additions, deletions or amendments making the file The most Up-To-Date and Comprehensive source of Telephone Number Information in the UK.

We add telephone numbers to our clients files under Our NumbersPLUS Service. The service is available via our Bureau and ADMAR OnLine Services.

more information on DE, DQR & XD Classifications