[TriLUG] OT - TWC bandwidth caps on the way?

[Rob Lockhart]

On Thu, Jun 5, 2008 at 2:02 PM, Rob Lockhart <rlockhar at gmail.com> wrote:

> On Wed, Jun 4, 2008 at 10:20 AM, <jonc at nc.rr.com> wrote:
>
>> 40GB won't endanger any VoIP carrier that I've ever heard off... VoIP
>> requires continuous low latency connections, but very little bandwidth.
>>
>> Vonage: 1hr = 300Mb (max)
>> FeatureTel: 1hr = 100Mb (max)
>>  "max" means all talking all the time - no pauses (like listening to
>> music)
>>
>> Vonage uses G711 codec which maxes out at 87 Kbps
>> FeatureTel defaults to G729 codec (voice only - no noise) which maxes out
>> at 31 Kbps
>>
>>
> Hi, Jon.   Vonage has three tiers of bandwidth you can provision: 30, 50,
> and 90kbps.  So, if we assume worst-case, 90kbps, one hour (bidirectional)
> traffic:
> 90E3*2*3600/8 = 81 MBytes.  Did I do the math right?  I assume 90kbps to
> take into account the signaling and framing overhead, etc.
> Now multiply that by 24 hours/day, 30 days/month you get 58 GBytes.
> Whoops!  So don't talk on the phone all month long.  :-)
>
> I thought G.711 would require the same bandwidth if background noise is
> sent from the far-end.  You're probably more familiar with whether Vonage's
> implementation of G.711 requires bandwidth for silences.
>
> I think I saw that the cap was on both upstream and downstream (aggregate).
>
>
To answer my own post:

http://en.wikipedia.org/wiki/G.711

G.711 Appendix II defines a Discontinuous
Transmission<http://en.wikipedia.org/wiki/Discontinuous_Transmission>(DTX)
algorithm which uses Voice
Activity Detection
<http://en.wikipedia.org/wiki/Voice_Activity_Detection>(VAD) and
Comfort
Noise Generation <http://en.wikipedia.org/wiki/Comfort_noise> (CNG) to
reduce bandwidth usage during silence periods


So the question is whether Vonage and/or other VoIP providers are utilizing
Appendix II.  Good luck getting them to tell you that!  :-)