WiFi calling is an operator feature where calls are diverted from the cellular network to a local WiFi network. But there are other options for making calls over WiFi networks:
- OTT application calling
- Operator WiFi calling
- MVNO VoIP calling
This is a well-known use case of using Skype, Viber, FaceTime or any other OTT service using an App for making calls.
The call will use the currently available data connection the phone has be it a local WiFi network or 3G/4G mobile network.
While this option is widely used and although in many cases it actually does use WiFi for placing those VoIP calls, it doesn’t fall under the definition of WiFi calling.
Operator WiFi calling
Operators that launched LTE networks and have IMS in their core, are using capabilities of latest mobile phones such as iPhone 6 and some of the new Android devices of Samsung and others to divert calls from their cellular network to WiFi.
The use case is mainly for overcoming connectivity issues in buildings or areas with limited cellular connection that do have a local WiFi network. In such cases, if WiFi calling is enabled on the phone, the call will be placed/received over the WiFi network.
This capability can be used by operators to reduce load on their network by utilizing WiFi networks where available.
From users’ perspective, nothing really needs to be done. User continues to use existing phone numbers for placing calls and is reached on his current phone number.
The cost of the service depends on how the operator decides to price the service. Typically it comes as part of the existing plan the user has with no change in billing of the user.
MVNO VoIP and Google Project Fi
The 2 options above are relevant for operators with LTE networks and OTT service providers but there are also MVNOs that ride on operators’ cellular networks.
Earlier this year Google introduced Project Fi. For introducing this service Google made sure it controls all 3 layers of the network, device and application.
For the network Google teamed up with Sprint and T-Mobile to use their cellular data. The other part of the network is WiFi, which depends on the quality of that WiFi connection.
For device, Google has its Nexus phones.
For application, Google combines phone dialer with interface for PCs and tablets so users can move between devices and not be restricted to mobile phone only.
By introducing Project Fi Google practically became an MVNO. To top that, Google introduced a billing model that starts at low cost and refunds users for unused data.
Traditional MVNOs can launch their own VoIP calling service in order to reduce operation cost and be competitive.
The solution for MVNOs would be to provide their customers with devices that have a preinstalled modified dialers (possible on Android only) that will perform all calls over the cellular data or WiFi. Handling of switching between the 2 modes will be the responsibility of the dialer application and routing of calls based on E-164 numbers will be the responsibility of the MVNO’s network.
PC and iOS applications can be added to this and the network can route the call to these applications.
A different type of service
The 3 types of services detailed above are different and one shouldn’t’ confuse between them. Moreover, OTT services will continue to be widely used along with the operator WiFi calling and MVNO services as they are today.
Having said that, there are differences in quality and user experience between these services as detailed in the table and following analysis.
In WiFi calling and MVNO VoIP, current phone numbers (E-164) are used. It makes no difference if user is on WiFi or Cellular, the network makes sure call reaches the user.
In Application calling, identities vary. In many OTT services, users have an identity provided by the OTT service provider, for example a Skype ID. In other cases such as WhatsApp, the identity is the phone number of the user. In all cases of OTT, calling is in the network of that OTT service providers and calling out of that network is typically possible through a premium service.
WiFi calling uses the current dialer of the phone as the service is a combination of the network and the device capabilities.
Application calling on the other hand uses an installed application and therefore has all the disadvantages associated with this including the fact that an OTT call may be interrupted by an incoming cellular call.
MVNO VoIP replaces default dialer on Android devices the MVNO sells and uses an application for all other cases.
Ease of use
WiFi calling requires only 2 things from the user: A one-time change of settings to enable the feature on the phone and to have the phone connected to a WiFi network.
Since OTT services typically work in silos of the OTT Island, it is required to use multiple applications. The installation of several applications is not a significant challenge for users but managing calls between those applications and knowing who to call using which application is cumbersome.
The handover between cellular and WiFi and the use of applications introduces challenges. Some implementations do a great job in this while others may have some user experience issues.
WiFi calling uses the phone dialer provided by the device vendor and therefore utilizes the HW capabilities of the device for handling the media in a battery efficient manner. Naturally, the usage of WiFi calling requires WiFi to be turned on. The actual calling over WiFi typically increases battery consumption but since this capability is part of the phone impact should be minimal.
In application calling battery consumption differs based on the capabilities of the application and what the device allows. Some applications have big appetite for power due to inefficient implementations mainly in the area of handling codecs and media algorithms such as echo cancellation while others are more efficient and are easy on the device battery.
Even if all applications are efficient, the fact that it is an application and in many cases, more than one, makes this option less battery efficient.
MVNO VoIP is similar to application calling of OTT as both are applications.
Cost of WiFi calling is typically tied to users’ cellular plan and therefore doesn’t reduce users’ cellular phone bill.
Application calling uses OTT model and is typically free in the network of the OTT regardless of user location (international/local). Even if call is placed through a premium OTT service, out of the OTT Island, cost will typically be lower, especially when compared to service provider international calling.
By using WiFi and cellular data when required MVNOs reduce cost thus can be even more competitive compared to operators.
WiFi calling and MVNO VoIP services are ubiquitous to the same extent the current phone system is.
Application calling is typically limited to the OTT Island with outbound calls through premium service. Problem for the user is to know who to call using which application.
When call switches to WiFi, all options are born equal. The quality depends on quality of the WiFi connection and what resiliency and quality enhancement algorithms are embedded in the application/dialer.
MVNOs that use cellular data have a similar issue as OTT with regards to ability to prioritize voice over other data passing on the same network.
Why this is important
It is important to recognize the fact that WiFi calling is not OTT application calling and these 2 are not interchangeable. Users want to have both.
The 3rd option presented here is an interesting opportunity for MVNOs to reduce their operating cost.
The introduction of Project Fi by Google is a significant threat to MVNOs and Operators.