VoLTE and HD Voice: it’s all about quality

Today AT&T launch their VoLTE (voice over LTE) service. Marketing it as high definition voice services, AT&T is focusing their messaging on the call quality delivered by HD voice. In promotional videos AT&T make a comparison with standard TV and HD TV, and demo audio clips of standard calls against HD calls. The marketing messages are about quality, quality and more quality.

As well as providing higher quality voice calls to customers, VoLTE is an attractive proposition for operators.  Having invested in LTE networks for data, the obvious way to save money is to run voice services over the same networks. There are some pretty impressive savings enabled by running voice and data on the same LTE network. According to one equipment vendor, these include 60 percent lower operations & maintenance costs, 75 percent lower site support costs and 65 percent lower energy costs.  Add this to the improved spectral efficiency (twice that of 3G / HSPA, and six times GSM) then it would look like the economic arguments for VoLTE make sense. 

With regards to the improved call quality Korean operator and VoLTE pioneer, SK Telekom has reported that VoLTE dramatically improves audio quality (able to handle 2.2 times wider frequency bandwidth than 3G voice). SK Telekom also claims much improved call setup times which range from 0.25 to 2.5 seconds on LTE, compared with a five second setup time on 3G. It’s worth pointing out that SK Telekom has over 8 Million subscribers using VoLTE service, which it has heavily marketed as HD voice, so it’s fair to say that VoLTE is a success in Korea.

From a billing and BSS perspective, VoLTE will create some interesting challenges.

Firstly, most operators will rate VoLTE calls as voice calls (e.g. start time, end time, A number, B number, national, international bands, etc). But while VoLTE calls are effectively voice calls made on a ‘data’ network the charging and billing systems will need to zero rate data transmission, and then apply voice rating rules. Also all of a sudden QoS (quality of service) is going to come into the voice equation. An issue with VoLTE is that mobile resources associated with each VoLTE call can be unpredictable, so a policy management system needs to dynamically manage these network resources to ensure the HD service promised is delivered.  And here lies a problem.

Research firm Heavy Reading recently ran a survey of 80 operators asking about the future of policy management. On the question of operator’s existing policy systems being ready for VoLTE – 60 percent of the operators surveyed said that they’d need to upgrade their policy systems, while 10 percent said that even upgrades wouldn’t solve the problem and they would need to replace their existing system.

Unfortunately this is nothing new.  From time to time we see mobile product launches with an initial offer of free service. While this can often be an altruistic promotion from marketing, in some (rare) cases it happens because the BSS (business support systems) is not ready –e.g. initial free service promotions because billing can’t collect and price required data records. Unfortunately a BSS stack that is not ready for VoLTE will not just be unable to charge and bill for the service, the VoLTE service may be in jeopardy as it cannot deliver the expected HD call quality. Delivering QoS on every call is essential for VoLTE, and to do this the policy systems need to be up to scratch to provide this from day one.

A look at the marketing messages for HD voice services – quality, quality and more quality, would tend to suggest that having policy to enable QoS for VoLTE isn’t a nice to have, it’s pretty much the foundation for the service.

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Martin Morgan
About Martin Morgan 13 Articles
With 25 years’ experience in mobile communications software, Martin has worked in mobile billing software since the early days of the industry. As such he’s been around long enough to have had numerous articles published. He has spoken at many conferences. He’s served on the boards of software companies and trade associations. At Openet Martin is responsible for marketing thought leadership and demand creation.

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