Debenhams used a one-day sale this week to test the potential of Twitter as a tool for answering shoppers queries.
The retailer issued staff in its Oxford Street Store with BlackBerrys to allow them to respond to shoppers during the sale on Wendesday.
Debenhams said it wanted to encourage messages on any subject, from requests for a jumper in a different size to queries for help zipping dresses.
"We believe it will give Debenhams a real commercial advantage," said spokesman Ed Watson. "Instant communication with our customers as they do their shopping is a tremendous asset. We intend to develop this approach in the future."
The retailer issued six staff with BlackBerrys and a laptop during the experiment.