T-Mobile: WiFi-Cellular Launch In September


T-Mobile plans to launch a Wi-Fi-cellular converged phone service in Seattle and potentially one other market next month on September 12th, sources say. More markets will follow soon after. The city of Chicago and the San Francisco Bay Area are the likely candidates for a possible rollout.

T-Mobile’s converged service is based on a standard called Unlicensed Mobile Access, popularly known by its acronym, UMA. The news that T-Mobile has been doing trials of services using the wireless convergence standard UMA have been slowly coming to light. Business Week points out a service targeted at in-home cell phone users called T-Mobile-At-Home, which seems like UMA, but the article doesn’t name the standard. Engadget had also posted information about the UMA trial.

We’ll see if T-Mobile can meet its planned launch date, but the company is eager to start deploying UMA given it can not only take a piece of in-home calls, but can also use UMA to handoff in its thousands of T-Mobile WiFi hotspots. UMA is a standard that enables the handoff of calls between cellular (GSM only) and unlicensed wireless like WiFi.

More than any other carrier in the U.S. T-Mobile has the incentive to use UMA — it ranks behind the top 3 U.S. carriers, only reported 613,000 net new customers for the second quarter of this year, and owns valuable WiFi real estate that it can use to grow those subscribers. The company would only confirm that UMA is one of the technologies that the company believes will help replace landline calls.

We’re not sure when T-Mobile will target any of its UMA services beyond what seems like an initial in-home calling launch, but adding hotspot coverage could be its trump card.

What exactly is UMA? It’s an international standard that has been in development for years by a consortium of carriers and companies. The technology works with both bluetooth and WiFi and uses dual-mode phones to roam between WiFi and cellular networks. Deployment of wide-reaching UMA services require UMA infrastructure in the network that companies like Alcatel, Nokia, Kineto Wireless, Motorola and Ericsson provide, as well as UMA software on dual-mode handsets developed by Motorola, Nokia, and Kineto.

Other companies have been trying to figure out the best way to handoff between various networks, and we pointed out startups like Divitas last month, but carriers are just starting to turn to UMA to solve the problem. Telecom Italia could launch a UMA service as early as the Fall, and TeliaSonera is considering UMA as well. In a major win for UMA, Orange is rumored to be choosing the option, though hasn’t announced its decision publicly. It’s not too hard to see why GSM carriers would opt for UMA.

As voice becomes even more of a commodity service and use of data services grows, the carriers all know that they need to adopt converged network services and offer easier ways to roam across networks. Most carriers are terrified of losing some of the revenues from cellular voice calls to cheaper WiFi voice calls, but as WiFi and other wireless networks grow, there is really no way around it. And because T-Mobile has been working on WiFi hotspots for years, it has a head start in this market. For the carriers that don’t have WiFi assets, UMA also gives the carrier a modicum of control as it makes this transition. Andrew Schmitt also points out how this gives the carriers a head start in the battle for the home with cable operators.

The carriers are so concerned about using UMA to control this shift, that likely UMA services won’t be able to handoff onto disruptive city-wide WiFi networks for quite some time. Handsets will likely be pre-programmed to roam onto approved WiFi networks only, and say, for subscribers living in a city like Mountain View, CA, with its city-wide Google WiFi network, why would a carrier agree to help switch all its customer’s calls onto a city-wide WiFi network?

It won’t, at least not for a really long time. This will likely be a major story going forward, and probably one of the reasons T-Mobile is launching its first UMA network targeted at in-home users only.



I run Lingo VoIP for the home phone and I also have a T-Mobile UMA device. I have never had a single issue with quality with either the VoIP or UMA devices within my network. Of course, I’m running a Fios connection with all the hardware upgraded (non-Verizon) to business grade hardware. The gateway is setup to guarantee a minimum of 90kbps up/down to the Voip device and another 90kbps up/down to the UMA device. This in and of itself is probably why it’s rock solid for me. The wireless access point is also setup for Wireless QoS (WMM) which prioritizes the voice traffic over wireless (useful for the UMA device). I run heavily loaded HTTP/FTP servers over this connection, so for me setting it up “right” was a must. Before setting up QoS, etc, I did experience quality issues. All of which are completely resolved with my current configuration. I hope this helps!


Avoid this service from t-mobile. They can’t deliver in several areas. I have ha trouble ticket open since August and it is Novoember. All the old Cingular towers also do not allow UMA/GSM handoffs so that will never work. Currently, UMA is down more than it is up in central california.


T-Mobile UMA mobile phone

Do you need to have a contract with T-Mobile to use the UMA technology. I am currently using Fido (GSM in Canada). I would like to know if the service provider needs to support UMA? Or can you use UMA on any network provided you have your own Wi-Fi hotspot.

If anyone knows please can you let me know.

Thank you.


For Jesse: There is no mention of SIP in the UMA specification documents on architecture or protocols stored at http://www.umatechnology.org/specifications/index.htm. If you have a link showing its use please share it.

The Wikipedia article http://en.wikipedia.org/wiki/UnlicensedMobileAccess makes metion of SIP but only that the transport supports IMS/SIP (of course).

My comment about foreign WiFi was referring to WiFi access points that are not owned by the quad-play provider that is the mobile phone carrier. It was not meant to mean in another country. T-Mob is planning to use its large network of APs, but not to allow your home AP to be part of the mix.

Lastly let us look at the issue about VoIP over mobile phones over WiFi or Wimax. The answer is yes this can be very good. And for those countries (e.g. USA) where there are unlimited data plans this makes economic sense. However most carriers have terms of service that explicitly ban VoIP. Could they really block it? Well they could try. But then the P2PSIP working party http://www.p2psip.org/ of the IETF probably has smarter people working on the opposite tack of the problem: how to prevent carriers from impeding your communication. Skype on a beefy Windows Mobile phone is pretty good, by the way. So it does work, at least for now.

Jesse Kopelman

John Egan and Alas4493, you guys are confused. UMA does indeed use SIP. There is a gateway (Alas4493 you noted this) at the GSM switch that converts from SIP to GSM signaling. It is also incorrect to say that there is no benefit to the GSM carrier with the use of foreign WiFi. The big issue with UMA is that the WiFi calls can be billed just like GSM calls. Thus the GSM carrier can charge you on a per minute basis if he so desires. That rate could even be varied depending on IP address, so that if you call from home or a carrier owned hotspot, the call is billed as off-peak, you call from elsewhere the call is billed as peak or even roaming. UMA is a huge benefit to the GSM carrier and only of peripheral benefit to anyone else.

Paul Jardine

I’ve commented before about UMA being a good (short term at least) solution for Mobile operators to prevent the eating of their lunch by VoIP companies.
We are going to see pure VoIP on a lot of phones once WLAN-enabled devices proliferate. That could be a big problem for Mobile operators if it works as well as Skype!
UMA is a poor substitute for VoIP and it will only be of value if it competes on cost for a WiFi-based call with VoIP (probably free!). Where UMA has an advantage is in the ability to hand-off to the cellular network. That is its only, but major, selling point. People will not bother to set up and use a VoIP client if they can get the same or similar service/cost using their current phone, AND it will continue the call if they have to jump in their car mid way through.
I also don’t understand Alas comment about foreign Wifi being no benefit?? What about GRX? Why can’t I set up access from foreign countries over the GRX network, thus extending T-Mobile UMA to all countries. Operators may choose not to do this, but it’s still their choice.
E.g. they could have a tariff where a UMA call to your local country was 1c/minute regardless of where you were in the world. The internet as one big cell!

John B

Unrelated to general discussion on UMA here, but related to the last comment by Alas, I’ve wondered: if the data transmission gets better, i.e. with less delay between reception and transmissions, what would stop Google from allowing Google Talk on the cellular devices (such as what they do today on Blackberries)? Far fetched, but, I think that would open up a large hole in the cellular phone companies’ marketing plans (especially if you’re getting the unlimited Blackberry data plan for $40 a month).


John cleared up some of the technical confusion in this thread. UMA is tunneled over WiFi, so all the stuff that your cellphone currently transmits over the air gets sent instead over WiFi, but it’s exactly the same stuff. That way with a small tweak to the phone and a new gateway at the carrier backend the carriers could make UMA happen. No SIP no VoIP no anything new. John also pointed out that 89 kbps upstream is needed, that can be iffy with low-end DSL in some countries e.g. USA.

Why do mobile carriers do it? So they don’t have to build out networks to provide good home coverage, so they can cater to the one handset generation, and so they dont get as much data channel contention in their networks. Is the cost of a WiFi call less? Sure doesn’t have to be – carriers can leave the billing systems just as they are.

Why do broadband carriers do it? The landline guys do it to fend off VoIP overlays (e.g. Vonage), in which case the mobile billing systems will be adjusted to respond to the ‘sent via UMA’ flag on the call. And to cement in the customer with one more appealing feature. E.g. The comments about TMO high churn – every additional product sold/delivered to a customer reduces their churn.

UMA over foreign WiFi, or any WiFi – no benefit to the carrier, only to the WiFi provider, provided it’s not free WiFi then nobody wins (apart from the consumer). It will take a disruptive influence to make UMA over anyFi happen.

QoS is a question with UMA. Cellphone protocols are optimized for bit-level degradation, IP protocols for resilience to packet drop. Tunnel them and what do you have… a 1500-byte packet is a lot of 20ms voice samples. The net net would be a good research paper. Anyone?

UMA is actually a hack. But it is a sweet hack, and even a cheap hack in telco terms, that can make some money, save some expense, stymie some competitors in the time preceding ubiquitous and operationally efficient SIP/IMS.


It might not even be relavent that a Cell Carrier is even involved here, or even IMS or UMA.
When these Wireless Mesh and WiMAX (Wireless Local Loop)networks are fully deployed in most major US Cities, the customer will only need to sign up for the Wireless Broadband Services for his Data (Internet and or Corporate links) and be able to DOwnload the new “Hullo” Softphone system and be off with a Voice service.



“Cingular has cancelled its UMA trial and is focusing on IMS/SIP VCC..”

I have also heard that the IMS vendor they had originally selected has come out and admitted that they would be able to provide the Handoff between WiFi and Cell.
Also true IMS functionality is really 2-3 years out. So what do these Cell Carriers do to address the new WIFi/Mesh and WiMAX networks that will effectively negate value of their Data services in major Metro markets, and begin eating away at their Voice w/VoiceIP features over WiFi.


Ram Krishnan


“VCC” is not “ways away” Several landline carriers are trialing VCC right now as we speak. And even though “UMA transport” can be used to access IMS applications, that can really work only if IMS client is downloaded onto the handsets.

Cingular has cancelled its UMA trial and is focusing on IMS/SIP VCC architecture. UMA has a short window – the fact that it is not based on SIP and all carriers are standardizing their core based on IMS/SIP is going to be its death knell. Right now, the only reasons why carriers are deploying UMA is that they would like to do market research/consumer behavior studies which they will then apply as they move to IMS


In the Stockholm area where I live, the city owned company Stokab is rolling out a major dark-fiber network, which in a few years time will extend to all homes and businesses in the area.

The company leases out the fiber to about 70 ISP:s on an equal footing, giving the consumer a lot of choise. This model will probably be adopted by other Swedish municipalities as well, in effect wiring up the whole country. As I see it, UMA will be a very important component of this scenario, and the discussion about any triple play advantages above is in effect invalidated. There will simply be only two services – fiber and (private or public) wifi in densily populated areas and cellular otherwise.


I have been using a T-mobile UMA phone for about a week and I love it. I have service in my apartment where I used to NEVER have service. Also when I am out at the bars most of the bars I go to have a WIFI connection so I am able to hook up to that and have GREAT service in the bar where I used to have little to no service. I think that T-mobile is moving in a good direction with this.

John Egan

I’d like to resolve some misunderstandings as to UMA, IMS, and what is possible with UMA.

First, UMA for this example, can be thought of as mostly a transport technology… to get voice (or data) to/from a terminal (handset, etc.) and a Mobile Carrier. The technology is based on mobile’s AMR CODECs (not VoIP) and GSM signaling (not SIP). During a WiFi connection, UMA terminals communicate over some form of internet connection (DSL, WiMAX, Cable) with a UMA Network Controller (UNC) located in the Mobile Carrier’s network. The UNC emulates a base station controller and base stations, therefore to a mobile carrier’s network a UMA terminal and its associated call looks like any other mobile call. This enables roaming and handover (switching from WiFi Access Point to cellular site and vice versa) while on a call.

UMA does not conflict with IMS. IMS in itself does not replace UMA. IMS is more of a network and applications oriented technology and so there really is no conflict. IMS does have VCC (Voice Call Continuity) in its definition which will enable cellular and WiFi dual mode handsets that use VoIP and SIP, but VCC is still “a ways away.” UMA can be used with IMS as a way to get a call/session into an IMS cloud through some form of gateway, just as any other legacy Circuit Switched call will be handled for many years to come. Meanwhile, IMS can still be used to deliver “rich media” and services to a UMA handset, albeit of a limited fashion when compared to handsets with an IMS client inside. But, once more, this is a ways away.

As to bandwidth usage and potential for poor communications… UMA voice calls need about 89 Kbps. Not much different than a VoIP call with SIP signaling. Each method can have higher or lower compressions, with UMA voice quality on par with VoIP at similar bit rates. Any internet problems or bandwidth fluctuation can disrupt a UMA or VoIP call, as I experience daily with Vonage. So that is not an option or solution.

T-Mobile seems to be continuing to focus on the younger crowd with their complete reliance on their mobile handset versus what can be thought of as the “hybrid” method that most others use (POTS at home, digital deskset at work, mobile outside). With UMA, when at home or the office, the mobile only user can use their WIFI connection and not use up their mobile minutes, leave their phone in its charger while speaking, and have a higher voice quality indoors. While at Hotspots, the user can once more save on minutes, enjoy whatever specials are given with the service, and have better or same as voice quality than other mobile users.

I believe UMA is not a technology that came and went before there was a market, but one that will grow in use as benefits to carriers and their highest use customers (those under 40) become evident.

Jesse Kopelman

Nick, all good points. I don’t know if the strategy is fundamentally flawed. Wall Street makes way to much of short-term developments and if you listened to them you would have to do a complete 360 on strategy every year (AT&T tried this policy with disasterous results). In the end, it is all about execution.


However, T-Mobile is a pretty big fish and I don’t know if anyone is big enough to really screw with them, let alone parent Deutsche Telecom.

I disagree.

The whole business model for Vodafone and T-Mobile as a worldwide mobile only carrier has been questioned by Wall Street. Vodafone and T-Mobile can’t beat former local landline monopolies with a mobile subsidiaries.

Vodafone got out of Japan with massive losses — they can’t beat NTT/Docomo, KDDI (with its own landline). Guess what Vodafone sold their Japanese subsidiary to Softbank that also owns Yahoo Japan broadband. Triple bundling.

They can’t win against France Telecom/Orange with their triple bundling in France. They can’t win against Baby Bells with their triple bundling in the US.

The business model for the satellite tv carriers was also very promising 10 years ago —- until the rise of broadband internet access kill their entire business model. Vodafone’s and T-Mobile’s business model faces the same fate.

Jesse Kopelman

Nick, I agree with you that UMA (especially at home) puts T-Mobile in exactly the same position as Vonage with regards to being at the mercy of network providers. However, T-Mobile is a pretty big fish and I don’t know if anyone is big enough to really screw with them, let alone parent Deutsche Telecom. This is why the combination with Vonage makes sense. Solid backing for Vonage plus enough customers for T-Mobile to make them really care about doing this right.


TMO US is rank #1 in CS (customer service) — i.e. when you call them to complain about their network, TMO gives you a bunch of free minutes. Nothing to do with “service quality” of their network.


This has to be targeting customers other than on family plans. It may include more than the low end (pre-paid) customers because singles and high usage business subscribers may benifit from this service too.

It also can reduce infrastructure cost because it will reduce the demand for additional cell site/equip to handle the growing voice and data traffic.

One thing about TM US bussiness I do not understand: If its service quality is ranked so high (highest among the majors, as high as VZW), and the price so low (lowest among the majors), why its churn rate is still so high (the highest among the majors and is 2.5 times of that of VZW) ?


Of course, the UMA technology doesn’t care what wifi network that you are on. But the business model and tech support issues are much more complicated.

If I am going to pay $x per month for a UMA service — and then my landline or cable broadband provider puts a QoS setting that makes it impossible for the UMA service to work reliably — who am I am going complain. I am going to complain to TMO.

So far — EVERY single UMA announcements have come from triple bundling business model. You have to subscribe to their mobile phone service, their landline service and their broadband service. Even AT&T/Cingular has a better business model with this UMA technology than the mobile only TMO US.

Every single day, Vodafone gets asked about their position on buying landline carriers to do triple bundling. You don’t see Vodafone talking about bundling UMA with hotspots with mobile plans. TMO US has a very questionable business model .

TMO has 25 million customers. Vonage has less than 2 million customers. Buying Vonage won’t help handset issue a bit.

Jesse Kopelman

Actually, with UMA you don’t are about what WiFi network your customers are on. UMA creates a SIP connection back to your GSM Switch, regardless, that you can capture as a billable event. T-Mobile can easily set things up so that calls are free on home WiFi, $0.05/minute on T-Mobile hot spots, and $0.50/minute on all other WiFi networks. The bigger issue is how many SSID will the handset be able to remember for seamless handover and how onerous a task will it be a for a user to enter a new one (and do you even let the user enter a new one). Then there is the talk time issue Glenn brought up. Without special support in the access points, you are not going to get better than 1 hour talk time, vs. 3+ hours with GSM.

If T-Mobile wants to be serious about this, they should consider buying Vonage. Being able to offer Vonage on a cell phone might just be compelling enough to work. Plus, they get a ready made brand and customers for this service which allows them to order larger quantities of handsets and get better prices. Contrary to yaromir’s comment, I have heard that Cingular is doing some UMA as a tie-in with AT&T, so that will be more pricing pressure on handsets. Still every little bit helps for a service you are targeting towards the lowend (UMA doesn’t make much sense for people with large voice plans).


Would like to add some points to the article:
– BT in UK is offering Bluetooth-based UMA service for around one year and there is even UMA-compatible Moto Razr available for purchase.
– It is likely that UMA will be offered only by T-Mobile in the US because:
— There is no UMA version for CDMA carriers available to date and no CDMA handsets with UMA support. Verizon and Sprint will wait for IMS/SIP technology to become available to provide seamless handover
— Cingular publically aknowledged that it would also go straight for IMS solution by-passing UMA.
– The main benefit of UMA is indoor coverage – something cellular networks are not good at
– With the US cellular plans offering allocated buckets of minutes for a flat fee, I don’t see how VoWiFi can steal some revenues from cellular. Whether you use your plan’s minutes or not you’re paying the same monthly fee. The voice is already commoditized. If you add to this free calls between family members or in-network free calls, plus after 9pm free calling and free week-end calls you’ll see that there is little left for WiFi to steal. In this case, WiFi is more about the service differentiation and convenience for users. While data over WiFi remains another topic to talk about.


In every announced UMA deployments so far — they are all coming from cell phone carriers with landline parents — BT, Telecom Italia, France Telecom/Orange, and TeliaSonera.

It’s all triple play — cell phone, landline and DSL — maybe with a dabble of the carrier’s own wifi hotspot access.

No carrier has ever announced UMA deployment yet — on cellular phone carrier + wifi hotspot combo. It will be interesting if T-Mobile USA will ever find the right business model for this technology — in light that they don’t own a landline carrier in the US and network neutrality debate going nowhere.

Glenn Fleishman

Related issue about roaming onto random Wi-Fi hotspots (paid, free, opportunistically available): The UMA handsets that are being released require a special Wi-Fi gateway protocol to have decent power management. Wi-Fi chips have gotten better about using very little power in standby modes–some use 2% of peak power–but there’s a lot of standby issues that need coordination from the gateway.

The Nokia 6136 UMA handset lists in its tech specs that UMA talk time is “up to 5.5 hours, if U-APSD is supported in the access point.” This is also, apparently, known as WMM Power Save, as a certifiable feature from the Wi-Fi Alliance.

I have never seen this as an advertised feature, but a number of major chip vendors offer WMM Power Save in their chips. This has to be enabled in firmware, too, obviously. In T-Mobile’s leak in Engadget, I noticed that users had to have a special T-Mobile Wi-Fi router.

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