[Asterisk-Users] VoIP Provider problems

[Max W Blackmer Jr]

> We recently configure an asterisk server to use with an VoIP provider
> to make calls to a PSTN. We use (voipjet, nufone, diamond....)
>
> We feel that we haven't got the quality that we hope. Sometimes our
> calls gets mute, or we feel communication cuts on our phone calls.
> We have got an QOS router (Draytek) reserving 1/2 of our wideband to
> the SIP an IAX2 protocols, and an ADSL line about 2 Mb.

ADSL has slower upload speeds than download speeds (your 2Mbps is
download). so you may have problems with your outgoing packets of
sound. g.711 codec (the default codec for most voip providers because
there is virtually no sound quality loss) uses about 84Kbps per channel
or simultaneous connection. For example if you have an Upload speed of
128Kbps. and you try to have 2 phone conversations you would need
168kbps transfer speed. That is 40kbps more than your upload speed.
This is a major problem with ADSL the upload and download speeds are
not equal.

Another potential problem is that your provider is over subscribed for
the available bandwidth. What this means is that when allot of people
are using their connection to your provider. The provider may not be
able to handle all those users at once and packets get dropped or
delayed. Dropping or delaying packets is very bad for VoIP especially
if they do not do QoS or ToS routing which most providers do not.

What is your upload speed?

Some other possibilities are to use some compression codecs which will
cause some sound quality loss like gsm or  iLibc and g.729 to pack more
calls in the limited bandwidth limitations.  Another option is to use
SDSL where the speeds of  both the upload and download are the same.

> We feel our quality decrease when in US are about 9:00 or 10:00 in the morning.

This time is when businesses in the us are opening and starting to do
business In the united states. Both for phones and Data.


> We do not know if this is it correct or all the people using VoIp
> provider feel the same quality?

This may mostly be in relation to you Internet provider and how many
hops you have to take to get to the VoIP provider and if they
oversubscribe their bandwidth capacity. One provider may be good for
one person with one person in a different  ISP than an ISP you have.
And you are even right next door to each other. This is as a result of
how the internet is connected and may not nessessarly be geographic.
For example you may be connecting to a server in your own city lets say
Chicago but you are actually routed to San Francisco then back to
Chicago. But it will not always take the same path the next time you
may be routed through New York. This is a simplification of how it
works.  The closer you are to a Tier 1 provider(they own the major
trunks interconnects) the less time it will take to get to your target.

> Anyone knows any provider without this kind of problems?

I have seen many Providers have both Good and bad connection links. It
is best to have a provider that routes with QoS and/or ToS within their
routers and have only one or two hops between your provider and a tear 1
provider.

> Witch provider do you use to get the best sounds quality?

It is not that simple. But you can begin by doing a traceroute to the
many providers at different times of the day. This will see the route
changes and time delays between hops to get to VoIP Providers gateways.

Hope this helps in understanding the problems involved with choosing a
provider.

Thanks,

Max