Watch CALLUP Wi-Fi calling video

Poor cellular phone coverage in buildings is a common problem in many parts of the world. In 2014, large mobile operators began to offer – or announced their intention to offer – voice communication via Wi-Fi hotspots, in a completely transparent way and without the need to install any app on the recipient’s phone. This method is known as  Wi-Fi Calling.

In other words, a mobile phone subscriber who suffers from poor coverage at home dials a number on his device, just as he does outdoors. He does not have to click on any app, and the mobile device automatically targets the Wi-Fi hotspot and the call is routed through the Wi-Fi, automatically and transparently, to the recipient. Wi-Fi Calling seamlessly takes the voice from the regular circuit switch path, and sends it via the data network path, while the user uses his regular phone user interface to make the call.

According to an ABI Research press release, “Mobile operators have started turning to Wi-Fi for voice support in addition to data, which further increases the value of public hotspots. Examples include AT&T, Verizon, T-Mobile and EE, which are either currently offering Wi-Fi calling services or planning to do so in 2015.”

In September 2014, Apple announced that the new iPhone 6 and iPhone 6 Plus support Wi-Fi calling through select carriers. New Android smartphones are also expected to support Wi-Fi Calling.

Wi-Fi Calling looks to be the next big thing, and will quickly be adopted by cellular carriers – large and small. It poses a slick alternative to the current femtocell solution – the small cellular base station that is designed for in-building environments, enhancing indoor coverage. And indeed, why should a cellular operator install an expensive femtocell at the subscriber’s home if the coverage is poor, if he already has a Wi-Fi hotspot that can be used for the same purpose?

The fact that today Wi-Fi hotspots are installed almost everywhere, may allow subscribers to use this method not only at home  but elsewhere as well. Indeed, in most locations the Wi-Fi network is password protected and the Wi-Fi Calling service will not be able to connect automatically. However, if the subscriber is in a location where he can ask for the password, he will be able to use Wi-Fi Calling. In other words, as soon as the mobile wireless device connects to any Wi-Fi network outdoors, the device will not only receive and transmit data, but calls as well.

Wi-Fi Calling not only makes it easier for the subscriber to speak over the phone where the signal is poor, it can also save him money, since the call is transmitted via data network and is not calculated according to minutes.

The ability to transfer phone calls transparently from the cellular network to available IP networks not only allows operators to enhance in-building user experience  and to save femtocell costs, but also removes a large burden from the network. In addition, this capability allows the operator to save roaming costs when customer calls are forwarded to another operator, such as when the subscriber is abroad or in remote locations where operator coverage is not good.

CALLUP joins this revolution with its innovative CALLUP Wi-Fi Calling solution, enabling cellular operators to switch calls automatically and seamlessly from cellular to IP networks through Wi-Fi hotspots. It enables subscribers to use their cellphone when the cellular signal is poor. It is done automatically – and the user does not feel that his phone calls are transferred through a  Wi-Fi hotspot.

Unlike any other solution, CALLUP’s Wi-Fi Calling is 100% seamless. The client is fully RCS compliant, giving the carrier advanced marketing capabilities. The client enables seamlessly routing the calls between the  IP network and the circuit switch networks. In addition, the client supports sending/receiving SMS over an IP network.

CALLUP Wi-Fi Calling provides complementary Rich Communication Services (RCS) during the call. RCS is a GSM Association (GSMA) platform (marketed under the brand name joyn™), enabling the delivery of communication experiences beyond voice and SMS, providing consumers with instant messaging or chat, live video and file sharing – across devices, on any network.

The solution allows operators to use and provide their subscribers with comprehensive, advanced RCS 5.3 compliant IP messaging services in any Wi-Fi-connected home, including those suffering from poor cellular coverage. The IP messaging services include VoIP and Video Calling, Video Sharing, Instant Messaging, Web Real-Time Communication (WebRTC) solutions, RCS Network API, Open Mobile Alliance (OMA) Presence enabler, Common Message Store, Best Efforts Voice, ViLTE, Wi-Fi offload solutions, seamless IP to SMS integration functionality and more.

CALLUP Wi-Fi Calling allows a seamless integration between “smart CS in-call services” and RCS on VoLTE with native RCS-enabled devices. No additional configuration or licenses are required. Providing these CS propositions allows the operator to increase the initial customer scope dramatically, and reduces the overall return on investment time for RCS and/or VoWiFi with the introduction of VoLTE on an IMS core.

The IP Communications Platform does not require an IMS core, and can be installed prior to the deployment of an IMS core. Once an IMS core is available and the VoLTE and VoWiFi features are handled with native VoLTE and VoWiFi devices, Roam Home continues to service the operator’s 3G devices, and will seamlessly become the operator’s RCS function platform for IP messaging functions for 4G users.

CALLUP Wi-Fi Calling uses DH 256-bit key exchange to generate a per subscriber key. It uses double encrypted heartbeats by using TCP over SSL and internal AES-256 encryption of client/server communication. SSL certificate pinning prevents MITM attacks, and internal server algorithms detect fraud and spoofing.