Bengaluru, Nov. 25 -- A rather frustrated and impatient customer called Decathlon's helpline one afternoon to ask about a delayed order, demanding an update. The voice at the other end, which began the conversation in English, switched to Hindi upon hearing the customer and assured him that the package would arrive in two days. The update seemed to calm the customer, who said "Thank you, madam" to the agent before hanging up.

There was only one thing off in what otherwise turned into a smooth call: the customer's assumption of the agent's gender. The voice was not female; it belonged to an artificial intelligence (AI)-powered voice bot.

That human-like bot was built by Yellow.ai, which manages sports goods retailer Decathlon's voice and...