[asterisk-users] Interesting observation

[Brent Vrieze]

I investigated Charter for our business phone systems and asked many of 
these questions of the sales person.  I was told they have a dedicated 
part of the bandwidth available that is used just for phone traffic. 

I could break out my college networking book and get you the frequency 
break down as far as what is used for IP and what is used for TV and why 
the upload and down load speeds are asymmetrical if I was motivated but 
I am not so you will have to take this for what it is worth. 

As cable is not a point to point system (cable is shared bandwidth for 
all users on that cable) that means all phone users will be using the 
same piece of spectrum on that cable.  This means that too many phone 
calls on that line at the same time could affect a Charter phone call. 

I do not know if they use analog or digital signals for the phones but 
if we use the cell phone system as an example they took down all analog 
towers because they could service more phones on the same bandwidth with 
digital.  I would assume that would hold true for the spectrum on a 
cable as well.  I would also find it hard to believe that they would not 
use off the shelf technology.

That being said my brothers in-laws are using it and are having no 
problems what so ever.



David Gibbons wrote:
> <snip>
> My understanding is that Charter 'telephone' doesn't use IP at all but
> rather uses some additional frequency spectrum on their cable network.
> Hence, the reason why faxing with their service is reliable unlike other
> providers who are *actually* using VoIP.
> </snip>
>
> I think what you're referring to is the general hesitance of the cable providers to call their phone service VOIP service. VOIP still has a negative connotation with most regular folks, so they don't want to negative PR.
>
> I'm don't have any facts, but I'll bet you a penny that they don't have a proprietary system using something /OTHER/ than IP to send encapsulated voice over 'additional frequency spectrum'. That would be prohibitively expensive to develop and pointless from a technical standpoint, given that IP telephony is already set to deploy and relatively mature.
>
> The reliability of faxing is based soley on network jitter and latency and codec compression. I've found that taking the compression out of the mix (using g.711 ulaw) and controlling the jitter and latency (something that's easy to do on a private network like theirs with QOS) causes faxing to be pretty darn reliable.
>
> --Dave
>
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-- 
Brent T. Vrieze
CIM Automation
Softare Engineer
507-216-0465