Your postcode. And that's the key to the direction in which telephone- based financial services are heading.
In their early days, direct sellers were regarded as "cheap and cheerful" alternatives to the mainstream, established financial institutions.
Not any more. Increasingly direct sellers are using the latest technology to become more customer-focused. All the operator needs is your postcode in order to see on-screen details of your previous dealings with the business.
Robert Wint of Co-Cam, a company specialising in the kind of system which delivers this information, says large companies have traditionally been poor at customer relations. You could contact them several times and not be recognised.
This problem has become more acute as many bank branches have closed down and more customers have been allocated to faceless regional centres. Increasingly though, Mr Wint says, technology will "re-introduce the quality of one-to-one client relationships".
When making an investment, people like to feel important. Call centres and client-focused systems put client data on to any screen at the touch of a key. If you walk into your local bank and the person with whom you are dealing is able to ask if you are happy with the PEP you bought by telephone last week, you feel that you are a "real person" rather than an account number.
Developments of a different kind are taking place on the Internet. If you are looking for an investment, you can spend hours viewing investment data on the Web sites of most big UK investment providers.
Many of them include planning tools and on-line calculators to help you make a decision. Some will even handle questions, although the answers may be stock rather than true responses.
Today, most investment Web sites provide information and take enquiries, but do not handle payments. Although the technology for secure credit card transactions on the Net is becoming available, for most financial services transactions it's still a matter of completing a direct debit form or putting a cheque in the post. That should change later this year as secure payment technology such as IBM's CommercePOINT comes on stream, which will enable secure bank transfers to take place on-line.
It is worth remembering that most of these Web sites and the tools that they provide are part of a sales process and the information may be biased.
If you want to refer to something you read recently in The Independent, but didn't keep the cutting, you could be in luck if you subscribe to AOL Europe - the local version of America On-Line. With a few mouse clicks you can access our on-line edition and search the personal finance and business pages of recent issues to track down the information and save it for reference.
For anyone investing in managed funds such as unit or investment trust PEPs, companies such as Micropal and HSW maintain Web pages with up-to- date performance data from main providers.
For example, if you connect to Interactive Investor (http://www.iii.co.uk) or Find, the financial services net directory (http://www.find.co.uk) you can find not only performance figures from Micropal or HSW but performance histories, profiles and analysis.
The basic services are freebut for more details you have to register, to comply with the Financial Services Act, confirming you have asked for the information and that you understand the terms on which it is offered.
Lionel Welch, operations manager at Interactive Investor, sees the next development as being "push" technology, downloading an intelligent screensaver carrying investment prices and data which automatically updates itself at regular intervals.
John Perceval, managing director of Omnium Communications, which created and developed Find, says that "when on-line banking getsunder way later this year, attitudes to payment over the Web will change rapidly and make it possible for Web sites to accept payment and complete transactions for value".
Another new technology which is looming over the horizon is interactive television.With the advent of digital TV the medium will provide a richer information environment - and television has the capacity to influence events in ways that the Internet cannot.
You can see how television and investment are already starting to connect if you have satellite or cable services and tune in to the two business channels, EBN and CNBC.
EBN, European Business News - part of the Dow Jones empire which publishes the Wall Street Journal - carries a mix of business and financial programmes, with regular market updates.
CNBC is much more market focused, and from early afternoon provides live coverage of the action on Wall Street, including the on-screen ticker showing virtually real-time prices.
In the world of digital television expect to see tighter links between the Net and broadcast services. In just a couple of years from now, expect to sit at home watching live news conferences and market commentary in a television window on your Internet screen.
One final statistic to consider from Charles Schwab, the giant US broking firm and parent of ShareLink, Britain's leading execution-only broker. This time last year, only 5 per cent of its dealing came from the Internet. Now the figure has passed 50 per cent. Will Britain be far behind?