T-Mobile subscribers must add the "Free Wi-Fi Calling" service to their rate plan, which is no additional charge since May of this year. Previously, the Wi-Fi calling still counted against plan minutes.
The Smart Wi-Fi application relies on Unlicensed Mobile Access (UMA) technology, which is based on the 3GPP (international GSM mobile standards body) Generic Access Network (GAN) standard. This is an extension of the GSM standard and is not available with CDMA networks such as Sprint and Verizon in the U.S. Of the two GSM networks only T-Mobile provides support for UMA today. However, with AT&T heavily investing in Wi-Fi hotspots through the Wayport acquisition and footprint expansion, it will be interesting to see if they become more receptive to Wi-Fi calling in the future. Additionally, Verizon and Sprint are unlikely to be receptive to this technology once they migrate to LTE, as both companies are pursuing other IP-based calling protocols instead of GAN and are looking to protect their average revenue per user (ARPU). Both companies have also declined to pursue Wi-Fi data offload to this point, but cellular network capacity issues may reach a critical level in the coming years prompting a change in direction out of necessity. Only time will tell.
Wi-Fi calling works by having the smartphone create a secure connection to the mobile network gateway by authenticating using EAP-SIM and establishing an IPSec VPN tunnel over the Wi-Fi network. The mobile network gateway presents itself to the mobile core as any other radio network controller, which turns the Wi-Fi or public IP network into another radio access network (RAN) similar to cellular towers. This also enables the full suite of mobile services to be available over the Wi-Fi network to ensure service parity and consistency of user experience.
|Smart Wi-Fi Calling Routes Calls Over Any Wi-Fi Connection|
T-Mobile users purchasing supported smartphones do not need to download the Smart Wi-Fi application, it comes pre-installed by the carrier (it's not available in the Android Market). Support for Smart Wi-Fi calling varies by model, so be sure to check out the list of supported Android phones on the Kineto website. Wi-Fi calling is enabled on the smartphone by default, but users can disable the service if desired by changing a single configuration setting within the application. A small blue callout bubble icon appears in the notification bar in the upper left corner when Wi-Fi calling is available. During an active Wi-Fi call the icon turns green.
|The Kineto Smart Wi-Fi calling is enabled by default,|
and provides easy configuration for users
Kineto provided me with an HTC Sensation on loan for a few weeks to evaluate the service. Overall, I found the experience to be extremely intuitive and simple for users. Voice quality over Wi-Fi was excellent, although that could be highly variable depending on the performance of the Wi-Fi network the user is attached to. Voice calls only require around 80 Kbits of bandwidth over Wi-Fi, so it should work adequately over most public hotspot networks. I trialed the service over multiple Wi-Fi networks, including my home, enterprise, coffee shop (Caribou), and an AT&T hotspot, and never experienced any call quality issues. In fact, compared to T-Mobile's cellular coverage, call quality was actually better over Wi-Fi in most cases!
There are multiple benefits of this solution to consumers. First, Wi-Fi calling improves coverage reception in most indoor locations by leveraging a high-quality Wi-Fi signal at the micro-cell level rather than relying on poor penetration from the outdoor macro-cell carrier network. Second, when users offload calls to Wi-Fi they don't count against their bundled plan minutes on T-Mobile and can help consumers reduce costly overage fees on limited minute plans or save money by switching from an unlimited plan. Third, individuals that travel internationally can eliminate expensive roaming charges. Finally, a side benefit is increased incentive for users to connect to Wi-Fi in general, resulting in a (typically) faster data connection for browsing the web, watching videos, or checking up on Facebook posts.
On the enterprise side, Wi-Fi calling can help reduce overall cellular plan expenses across the organization by leveraging investment in corporate Wi-Fi networks already in place. Many teleworkers also work out of locations with public Wi-Fi frequently, such as coffee shops, cafes, and bookstores. In addition, Wi-Fi calling can help enterprises avoid the expense of in-building cellular coverage enhancement with cellular repeaters.
I caught up with Steven Shaw from Kineto Wireless at Interop, NY 2011 and asked him a few questions about Smart Wi-Fi.
Revolution or Evolution? - Andrew's Take
Wi-Fi calling is a clear benefit for both consumers and enterprises. It offers improved indoor coverage utilizing Wi-Fi networks, reduces minute plan usage and expenses, offers cheap international calling, and the implementation by Kineto is seamless and intuitive. There is really no reason not to use this service if you are T-Mobile subscriber in the U.S. Kineto also has a large presence in Europe and predominantly GSM cellular markets.
It's disappointing that U.S. based carriers other than T-Mobile have been unresponsive to this service to-date. I'm not sure Wi-Fi calling is a compelling enough service for users to switch carriers today. But with mobile data demands only increasing and the emergence of Hotspot 2.0 roaming between macro cellular networks and micro Wi-Fi networks, Wi-Fi offload strategies will become more predominant. This provides opportunities for carriers to improve indoor coverage by leveraging existing private network infrastructures. Whether this will materialize is yet to be seen. One thing is for sure, the technology exists today and it's an issue of business development and market approach by the carriers holding this service back. Perhaps pressure from over-the-top voice and SMS services like Google Voice, Skype, and Facetime will compel the carriers to keep pace.
For more information:
- Kineto Wireless
- Smart Wi-Fi powered by UMA
- Wi-Fi Calling Overview and Smartphones Supported
- Kineto Case Study - Enterprise Benefits of Wi-Fi Calling
- T-Mobile Wi-Fi Calling Support Document
Full Disclosure - Kineto Wireless provided an HTC Sensation smartphone and pre-paid T-Mobile SIM card on loan for review of their Smart Wi-Fi application and service. However, all opinions are purely my own and I was not otherwise compensated for this review.