Voice and LTE: What’s An Operator to Do?
LTE networks are being launched in some countries, while in others bid documents for spectrum in which LTE networks are to be deployed are being prepared, or soon will be. One of the controversial questions LTE operators have to address with significant implications for their technology, investments, choice of vendor, and business plans, is whether and how to offer voice services to their LTE customers.
Relatively little attention has been paid until recently to voice over, or more broadly for LTE customers. Broadband data and video services have received all the attention and glamour. Nevertheless voice (especially when combined with the other even more narrowband service SMS) still accounts for the great majority of mobile operators’ revenues and is expected to represent up to about 2/3 of these revenues for several years to come.
Initially, the first LTE services are expected and planned to be broadband data, using dongles and embedded modems for and in (respectively) devices such as laptops, netbooks, and tablets. Later LTE handsets will become available that may be used as primary mobile phones as well as terminals for broadband data and other non-voice applications and services.
Several options have been proposed for providing voice services to LTE customers. While this list may not be exhaustive, the main alternatives that have emerged include:
- CSFB (Circuit Switched Fall Back) – CSFB works by using the network to alert the user during an LTE session that a voice call is incoming. The user can then take the call by dropping back to a 3G or 2G network.
- VoLGA (Voice over LTE via Generic Access) which is GSM signaling over IP, connected to an existing legacy 2G/3G circuit code and mobile switching center (MSC).
- Gateway Solutions – These solutions are proposed by Nokia-Siemens Networks (NSN) and Mavenir Systems in collaboration with Acme Packet.
- IMS (IP Multimedia Subsystem)-based VoLTE has been endorsed in the 3GPP- and GSMA- backed One Voice initiative by Vodafone, Verizon Wireless, AT&T, Telefonica and other major mobile operators to deliver SIP-based voice and messaging services over LTE radio Access Networks (RAN). The expectation is that all other approaches will either be interim, or non-starters. Of course a key question is how long is “interim”.
LTE is not going to be a ubiquitous service any time soon. There will be coverage holes for many years. In these holes, subscribers will in any case have to receive service from the legacy core while roaming on 2G/3G networks, depending on multimode devices (e.g. HSPA/LTE) for this purpose.
As of mid-2010 there does not seem to be a consensus among operators about how they will deliver voice services over time to their future LTE customers, although ultimately when LTE networks become quasi-ubiquitous and handheld LTE devices common VoLTE is likely to be the solution.
Meanwhile, at least in the opinion of this writer, it does not seem that an interim approach based on CSFB will prove to be attractive, since it can only offer a lower quality voice service than customers are used to already. The prospects for VoLGA also seem rather dim, since among major operators it is only being supported by T-Mobile (Deutsche Telekom).
The first LTE customers are therefore likely to be either:
(a) Using LTE networks only for broadband non-voice services with laptop/netbook/tablet-type devices, relying on 2G/3G services for mobile voice, presumably with some bundled billing discount, or
(b) Dependent for voice services from their LTE devices upon VoIP clients supplied by a third party, with or without the specific endorsement of their mobile services provider. Whether Gateway solutions will also become common, such as those proposed by NSN for their operator customers and by others independently of NSN network equipment, is unclear.
Full Article: http://www.bmi-t.co.za/?q=content/voice-and-lte-–-what’s-operator-do
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