With growth slowing in the $358 billion handset market, Apple Inc. and Samsung Electronics Co. are developing digital watches that allow people to make calls, check map coordinates or monitor their physical activity.

They might want to talk to Sony Corp., whose feature-laden SmartWatch, on sale for more than a year, isn't mesmerizing the masses. Priced at ¥10,000 to ¥13,000, Sony's 1.3-inch touchscreen watch wirelessly connects to Android smartphones using Bluetooth technology. The gadget alerts users to calls and allows them to reply to email messages or texts with an array of prewritten responses.

The SmartWatch, about the size of an iPod Nano, is a slightly smaller successor to Sony's LiveView watch. Introduced in 2010, it had more limited features and was hobbled by kinks. The newer model is more stylish, although users can't enter messages and it sometimes requires daily recharging and a stable connection to tell time reliably.