DUBAI // You come home from the mall with a car boot full of groceries, maybe some new shoes – and a mobile phone full of annoying text advertising.

And it’s your fault. All you have to do to avoid it is battle your instinct to give your mobile number when asked at the check-out, and your privacy is intact.

But Justin Thomas, associate professor at Zayed University, said many shoppers felt it was part of the transaction – as necessary as passing the credit card.

“From a psychological perspective I think there is an element of cognitive dissonance,” he said. “I give you the item I want to buy, I give you money or my credit card, then you ask for my number.

“It almost feels uncomfortable to say no. Most shop assistants ask for it in such a matter-of-fact way that I imagine people hardly ever say no. I always do.”

Many shoppers at Dubai Mall thought they were obliged to give shops their contact details.

“I thought it was a bit strange when I came to Dubai five years ago and a shop assistant asked for my number after a I bought something,” said Briton Paul Tomkins, a project manager for a building company.

“It’s something I’ve just got used to now so I don’t give it a second thought. I didn’t realise that the shops use these numbers to send adverts so I’ll be refusing to give it out in future.”

Jane Ashwin, a British housewife, felt many customers were pressured into giving their phone number.

“When you buy something, the sale assistants always say that you need to provide these details as it’s required for the warranty,” she said.

“I always feel as though I don’t have a choice, so I end up giving it out.

“There should be notices placed on the cashier counter informing people why they need to give out their numbers, and confirmation that it will not be given out to advertising companies.”

Imran Anwar, a Pakistani legal administrator, believes that shoppers should be given a clearer idea of their rights.

“At the moment, people place too much trust in these businesses to make sure they don’t give out customers’ numbers to advertisers,” he said. “It’s really annoying when I get these unsolicited text messages for stuff I haven’t signed up for. People should at least have the full information that their details will be used by advertisers and if they still want to give their number, they can.”

Shop assistants insisted that phone numbers were needed for warranty purposes.

“We ask for the numbers and email addresses as a back-up in case the customer loses the hard copy of their warranty,” said a sales assistant at an electronics store.

A fellow sales assistant at a computer store said it was not uncommon for customers who had lost their warranties to ask for a new copy.

“With the contact number we can check their details and print a new warranty if it’s required,” he said.

After many complaints about unsolicited text advertising, the regulatory watchdog has urged residents keep their phone numbers to themselves.

nhanif@thenational.ae