Hong Kong’s second and fourth largest mobile operators have introduced WiFi calling on select 4G iPhone models.

3 Hong Kong, the territory’s second largest mobile player with a 25 per cent share of the market, has launched what it calls voice-over-WiFi (VoWiFi) for its 4G customers using “most popular” smartphone models. These in fact are limited to the iPhone 6 and Plus, 5S and 5C.

The operator, part of Hutchison Telecommunications Hong Kong (HTHK), said the launch comes after extensive testing and claims to have the support of Hong Kong’s largest WiFi network, with 16,000 hotspots.

SmarTone, the fourth ranked operator with a 15 per cent market share, also has introduced WiFi calling for customers using iPhone 6 models. The handsets need to be running on iOS 8.3 or above. SmarTone said it has more than 11,000 hotspots.

Both operators said calls automatically switch seamlessly between WiFi and mobile networks when voice over LTE (VoLTE) is activated.

The calls will count as local voice minutes on customers’ service plans. 3 has introduced a value-added voice plan with 1,000 minutes of extra voice for HKD10 ($1.30) per month.

HTHK COO Jennifer Tan said it launched VoWiFi because “we are well aware customers are always looking for a better voice calling service”.

A 3 representative told Mobile World Live that Android capability “is coming soon, but it’s not yet ready”, while SmarTone said it doesn’t plan to offer the service for Android handsets, noting that it has an app called ST WiFi Calling that Android users can install and use to make WiFi calls.

Cisco forecasts that VoWiFi minutes will exceed VoLTE usage by 2018, when VoWiFi calls hit four billion minutes.