Minimum Spec
You can get
VoIP to work quite well with a surprisingly low
spec'd broadband service. The minimum you really need is 128/64 (ie
128kbs downstream and 64kbps upstream). The most popular
codec is G.729 which uses 31.2 Kbps
downstream and 8 Kbps upstream. So as long as you are not thrashing the
internet at the same time as making a phone call, you should be fine.
You can get Quality of Service
QoS software in your
router that can prioritise the upstream leg,
but it wont have any impact on the downstream leg. The only way therefore
to successfully be able to surf the net and make a VoIP call is to ensure
you have enough downstream bandwidth to cope with both. You can read up
more about QoS on the
router
page.
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ADSL
VoIP works just fine on ADSL 1 and ADSL 2. You
will need a line filter between your PSTN wall outlet and the VoIP ATA if
you are using a SPA-3000. You do not need a line filter between your ATA
and your phone, nor a line filter between your ATA and your Modem.
If you want to split the phone line for 2 handsets or a fax machine, you
should do this after you have been through the SPA. ie Wall=>ADSL
Filter=>SPA=>fax/phone splitter.
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Cable
Both Telstra and Optus cable are great choices
for both internet and VoIP.
Telstra
Telstra cable requires you to login to bigpond
with your bigpond username and password before you can use the service.
If you don't have a
router, then this logon procedure is done by
your PC when you boot up. When you install VoIP, you will need to
purchase a router and configure the router to login rather than the PC.
This is because there is no way that an ATA can login to a broadband
service for you. If you have Bigpond, make sure you purchase a router
that allows you to login to your ISP.
Optus
Optus Cable limits the downstream bandwidth when
you exceed your monthly limit. If you are using the G.729 codec, you will
still be able to successfully use VoIP when you have been limited by
Optus, but you wont be able to surf the net at the same time.
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