Telecoms Announce "One Voice" Initiative To Promote LTE Wireless Broadband Stand

suraj.sun writes to mention that Long Term Evolution (LTE) networks may have just gotten a boost over WiMax in the battle for wireless broadband dominance. A group of telecom companies has created the "One Voice" initiative, designed to promote a standard that will provide interoperability for broadband voice and SMS. "LTE has been fine at supporting data, which uses IP-based packet switching. But it's faced challenges trying to incorporate traditional circuit-based switching voice and SMS services onto IP-based networks. One Voice is the group's attempt to resolve that issue. The new specification will use existing functionality known as IP Multimedia Subsystem (IMS), which already defines how to provide data, voice, and other content over an IP-based network. IMS was established by the 3rd Generation Partnership Project (3GPP), a group comprised of telecom industry associations trying to set standards for 3G mobile networks."

Re:SMS?

[sg3000]

Strictly speaking, SMS has more in common with voice than the regular data traffic (email, http, etc). SMS travels across the digital control channel within the broadcast messages for the voice channels. Within the core of the network, it's transported on the SS7 network, which is the control network used for voice. So it is segregated from regular data.

IMS-based instant messaging will adapt fine to a 4G network, but there has to be some sort of standardized SS7 and IP gateway mechanism for the IMS network. It's not hard, but it's easier for operators if there's a reference that the operators can use.

Re:SMS on the Internet, efficiency issues.

[TheRaven64]

When I was in Japan back around 2003, SMS had been completely replaced by email there. All phones supported email, and when you received an email the phone woke up. If you've got an IP network, it's pretty easy to just use an existing protocol, like XMPP or email to deliver messages. There are existing email to SMS gateways, so this seems like an obvious way of doing it. Only support email on your LTE phones and have the carrier run a gateway that turns SMS received for the phone into email and emails addressed to {phone number}@carrier.com into SMS for legacy networks and maybe add something to the phone's UI that lets it pretend to still be sending SMS and fills in the @carrier.com bit of the email address for you.

Re:VOIP?

[cuby]

Voice is much more complicated than it seems.
You have to tax calls, manage pre-paid and post-paid plans. You need to have rules for roaming between operators and types of access, guarantee privacy, but also ensure the the authorities can listen and trace calls if ordered by a court of law. You have QOS, policy enforcement (ex: terminate calls if you have no $$), call forwarding, ...
And all this must be integrated to other existing operators seamlessly and without braking any existing features.
It is very complicated stuff.

Re:VOIP?

[tengwar]

Not a daft question, but it's not a separate standard. SIP is the closest thing we have to a VoIP standard. IMS is the specification of how to fit SIP into a GSM network. There's a lot that SIP doesn't specify - e.g. authentication and authorisation (GSM networks need to use SIMs and the corresponding HLR/HSS back end databases), accounting and billing, gateways to circuit-switched voice etc.

LTE, WiMax, IMS, UMA, One Voice, and VoLGA

[Zigurd]

LTE and WiMAX are the main competing 4G technologies. Both LTE and WiMAX are all-IP networks. No circuits. No dedicated channels for voice. If you run voice on 4G it will be packet voice no matter the other technology choices.

One Voice is what this consortium is calling IMS for 4G. IMS uses SIP for signaling. That makes IMS more like the kind of packet voice you find in Asterisk. Except IMS includes a lot of additional standards that, among other things, enables it to replace the signaling used in circuit switched networks and still interface to those networks. Some people favor IMS because it is the officially accepted 3GPP standard for these types of networks. Other people don't like IMS because it is too complicated and includes a lot of stuff that is unlikely to be used, including stuff like using SIP to initiate Web sessions so you can charge for them. Not that anyone would accept that kind of product.

The other consortium that pushing a voice call standard for LTE is called VoLGaA Forum. VoLGA stands for "Voice over LTE General Access." It works like UMA, which is a way of extending the circuit switched mobile signaling over IP. So you can buy these UMA "femtocells" - a really small cell site - and put them in your home or office and hook them up to your Internet service to extend mobile access to those locations. VoLGA is UMA scaled up to the whole network. Pretty suave, especially for the networks that already support UMA - you can re-use a lot of the same systems.

WiMAX never flirted with UMA (as far as I know) and I think most WiMAX networks that support voice will use IMS. Which is what One Voice is promoting for LTE. So that's no disadvantage for WiMAX.

You may be thinking "If it's all packet voice, why don't I put a SIP client on my smartphone and use my company's IP PBX? Or, why don't I use a smartphone Skype app?" That's called an over-the-top service (OTT). Which is why SMS is so... "important" to this discussion: The only thing you lose by using an OTT service, is SMS.

Re:Isn't this what SIP is for?

[jonwil]

Firstly, you need stuff to handle routing your call to those on other networks (PSTN, other mobile networks, GSM/UMTS/CDMA/etc).
Secondly you need stuff to handle hand-offs when you walk from the LTE coverage area to a GSM/CDMA/UMTS coverage area.
Also you need to be able to charge differently for voice and messaging (voice on mobile networks also has government taxes and charges that dont apply to data in various parts of the world)