Workers will attach a memory card containing the data to bird's leg and let nature take its course.
Experts believe the specially-trained 11-month-old pigeon will complete the flight in just 45 minutes - and at a fraction of the cost.
Unlimited Group boss Kevin Rolfe said: 'It might sound crazy in this day and age, but we're always looking for new ways to move our business forward and we think this might just work.
'For years we've struggled with the internet as a method of communication. It's fine for emails and correspondence, but we need to transfer a lot of data from office to another and find it often lets us down.
'To send four gigabytes of encrypted information takes around six hours on a good day. If we get bad weather and the service goes down then it can up to two days to get through.
'We started looking at other ways to solve the problem and discovered that carrier pigeons could do the job a lot more quickly.'
If the first pigeon flight is a success bosses will employ Winston and some of his friends to make a weekly trip between the firm's two offices.
The Unlimited Group is a South Africa-based company offering insurance and financial products to entrepreneurs.
Its head office is in Durban on the country's south-eastern coastline, while its main call centre is 50 miles north in Howick, outside Pietermaritzburg.
Winston is owned by a keen pigeon fancier who lives a short distance from the call centre and has already flown several test runs without carrying information to ensure he is familiar with the route.
Kevin added: 'For security reasons the information on the memory card attached to Winston has to be very thoroughly encrypted, as it contains personal details of people who call our centre.
'With modern computer hacking, we're confident well-encrypted data attached to a pigeon is as secure as information sent down a phone line anyway.
'There are other problems, of course. Winston is vulnerable to the weather and predators such as hawks. Obviously he will have to take his chances, but we're confident this system can work for us.'
Broadband internet in South Africa is not as widespread as in the UK.
Although recent advances in technology have seen it rolled out in most major cities, it remains costly to use and the service can be blighted by adverse weather conditions and power cuts.
Kevin added: 'We're not blaming anyone for the problems we've experienced with the internet, but we're keen to try and find another solution.
'For a firm like ours that transfers a lot of data regularly the costs of doing so can add up.
'If Winston can do the job as efficiently then we'd be silly not to think about using him instead - especially as he'll only cost us a little of bird seed to run.'
Carrier pigeons are specially bred for their ability to find their way home from wherever they are released.
The birds were believed to have been used for the first time in an organised manner in the twelfth century by the Mongol leader Genghis Khan.
Pigeons were later used extensively during World War I to send message between trenches on the Western Front.