The Roaming Revolution: VoLTE and VoWiFi Calling

August 21st, 2017

With the emphasis around the next generation wireless improvements, one thing remains clear: Regardless of which generation network you have deployed, subscribers are going to take, and use, their wireless devices on networks owned by other Mobile Network Operators (MNOs). A particularly large expense in an MNOs’ or Mobile Virtual Network Operators’ (MVNO) balance sheet is the cost involved when subscribers roam on other wireless networks. Therefore, anything an MNO or MVNO can realistically do to keep its subscribers from using other wireless networks for voice calls will have an immediate and favorable impact on the bottom line.

Wi-Fi and LTE Calling

Each year, the Cisco VNI report forecasts the global MOU for VoLTE, VoWiFi and VoIP (over wireless access). Each year the forecasted use of Voice over Wi-Fi has increased to the point where its use now exceeds forecasted VoLTE use. And in a few short years, VoWiFi is projected to be double the volume of VoLTE:

Projected Alternative Access Calling uptake, VoWiFi, VoLTE and VoIPFigure 1: Projected Alternative Access Calling uptake. Source: Cisco

One of the drivers behind this explosive growth in VoWiFi is that MNOs and MVNOs recognize that Wi-Fi and LTE Calling slashes roaming expenses.

Slash your Roaming Costs

Let’s take a brief look at how Wi-Fi and LTE Calling work together to slash your roaming costs. It is very important to note that implementing Wi-Fi and LTE Calling does not impact your ability to charge subscribers for using their phones out of region, it just eliminates your additional expense of allowing them to!

The following two tables help illustrate the magnitude of cost avoidance Wi-Fi Calling generates:

wifi calling

When your subscriber’s calls are seamlessly sent over Wi-Fi, roaming expenses are avoided entirely. Your subscribers’ leg of the call is backhauled via an Internet enabled Wi-Fi connection (at a hotel, a coffee shop, a home, an office, etc.) to your switching core. No part of your subscribers’ leg of the call touches the competitor’s wireless network. This represents a 100% expense reduction! And as the following chart indicates, implementing Wi-Fi Calling means a healthy improvement to your bottom line.

vowifi savings

And in those locations where Wi-Fi is not available, subscribers can seamlessly utilize any available LTE data channel instead of a circuit switched voice channel. The following two tables help illustrate the magnitude of cost avoidance LTE Calling generates:

lte calling roaming

When calls are conducted over an LTE data channel, the calculated cost per minute to use the LTE data channel can be up to 89% less than the cost of that same call roaming on a circuit switched wireless network! As the following chart indicates, implementing LTE Calling also means a healthy improvement to your bottom line.

lte calling roaming


Implementing Wi-Fi and LTE Calling

Sonus has the right solution to rapidly deploy Wi-Fi and LTE Calling for both MNOs and MVNOs.

Sonus Mobile Client: The Sonus Mobile Client is a downloadable client for Android devices that enables a true native calling and messaging experience. Your subscriber’s Android experience is completely unchanged.


The Sonus Mobile Client is available for, and works on, all Android operating systems from Android 4.1 onwards, regardless of handset manufacturer or model. The Sonus Mobile Client complies with mobile industry standards for Wi-Fi Calling and is compatible with standard IMS infrastructures from nearly every leading mobile core network provider, including the Sonus Virtual Mobile Core.

Sonus Virtual Mobile Core (VMC): The Sonus VMC eliminates the need for complex, expensive, and time consuming IMS deployments by combining standard IMS functions into a single virtual software solution. The VMC also supports the Sonus Mobile Client as well as other native clients provided by device manufacturers, such as those on the Apple iPhone 5c and later, and a few high-end Android phones. By deploying the Sonus VMC, MNOs and MVNOs can implement Wi-Fi Calling within 100 days.


Wi-Fi and LTE Calling can now be provided to all your Android subscribers at a fraction of both cost and time previously required. The question therefore is no longer whether you can justify the investment required to support Wi-Fi and LTE Calling for your customer base. It is now about whether you can afford not to!

Meet Sonus at LTE Voice this October.

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