Paul Warner wrote:
> Hi Guys.
>
> The company that I work for wants to do a proof of concept VOIP via
> ADSL. Yeah I know ADSL in NZ is not the best for VOIP but it can be done.
>
> At work we have a Nokia M21122 and at home I have a DSE 1149 router.
> Both I suspect don't support this too well.
>
> I have done testing before and got the phone off our PBX system to come
> up but no speech when called .
>
> We asked our parent in Oz and they say that they have one site doing
> this over there using a VPN over ADSL set up .
>
> I suspect that our ADSL routers here at work and at home may not support
> VPN???
>
> If we buy a couple of routers that do can any one suggest an item and
> an approximate price.
> If we get the routers do we have to get our ISPs (Xtra work and Orcon
> home) to setup and VPN tunnelling system for us??
>
> Thanx in advance.

It does work - I've used e.g. Callplus' iTalk service quite succesfully
over Xtra DSL - but the 128k upstream can limit quality unless you use a
low bitrate CODEC. This of course will limit voice quality as well.

The 64kbit/s G.711 CODEC which provides PSTN quality sound consumes
around 80kbit/s, leaving you with very little room on the upstream pipe
so some form of QoS traffic management will be necessary.

As for the routers, it depends on the requirements of your VoIP devices
as to which ones are suitable and how they should be configured. NAT can
make things difficult, for instance, but the newer devices can make
their way through that.

-- 
Juha
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