But the rise of the internet would change the way business was done - including moving some of it out of the office altogether.
"Over the next five to ten years it just snowballed and it was possible to work from home and nobody would notice the difference," says Caroline Wylie, of the Society of Virtual Assistants (SVA).
"When I first started back in 2004, the way you would answer phones remotely is you would have ISDN lines, 40 different phone lines going through a building through the ISDN and into your phone system.
"The system cost over £5,000 to install and cost about £200 a month to run. These days you can replicate that using VOIP (voice over internet protocol) and you can put the same system in for a couple of hundred pounds and it would cost you about £10 a month to run."
Today the virtual assistant (VA) industry in the UK can count about 2,500 active members, working for more than 13,500 small businesses.
The majority are "solopreneurs", working from home, often with a background as a PA and 97% of them are women, according to the SVA's survey of its members.
Caroline describes them as "administrative professionals that work on a freelance basis", providing a wide range of services, from secretarial and marketing to administration and book keeping as well as the "mental load stuff" like arranging holidays and children's Christmas presents.
The internet revolution has brought demands for more social media skills, blog writing, email marketing and search engine optimisation. VAs can find themselves managing Twitter and Facebook accounts and transcribing captions for YouTube videos.
"Social media marketing has become such a huge thing now and so important to businesses in terms of making sales. They need someone who understands that, it's not necessarily a skill they have in-house," says Caroline.
"Lots of business owners are really great at what they do. They have got fantastic skills of running an estate agency or being a surveyor, but they never thought they would be doing their own admin. That's not what they signed up to."
For businesses which can't afford or don't need a full-time employee, a self-employed VA can offer a flexible alternative. They can be hired when needed but not when business is slow.
Rates of pay vary according to experience but typically will be between £15 and £30 an hour - with £25.34 an hour being the average rate.
Offshore VAs offering cheaper rates can be a false economy, says the SVA, as while the hourly rate may be low, it takes much longer to carry out tasks and businesses must check that any data handling complies with GDPR requirements.
Annabel Kaye, of KoffeeKlatch, which specialises in freelance contracts, says: "Clients need to be aware that outsourcing their work doesn't outsource their responsibilities in terms of data compliance. It is down to the client to make sure their data stays safe and there can be serious consequences if there is a data breach of personal information."
SVA's own survey suggests that, despite being "virtual", many businesses will look for a locally based VA with good local knowledge.
VAs are highly skilled professionals, who have usually worked in an office, often as a high level executive assistant.
They may have chosen to become a VA to escape long commutes. Many value the flexibility offered in terms of hours worked and the variety of clients they can work for.
But they are keen to stress VAs are not "doing it for pin money" and the majority are in it for the long-term.
With the likes of Siri, Alexa, Cortana and Google Assistant muscling in on the name "virtual assistant" online - is the SVA worried?
"There have been secret mutterings about changing the name but we have spent so long trying to claim it. In general terms, people know who you mean and it's been a long hard battle to get there!", says Caroline.
She expects that as technology continues to advance, VAs will be carrying out less basic admin tasks because transcription devices and other programmes will get better.
But the "human element" offered by VAs will always be essential for organising and setting tasks, working out processes and for that all-important insider knowledge.
"VAs are specialists in making the virtual relationship work, so it should be as easy as working with someone sitting beside you."