Sipgate G711A - what packet size?

I'm using a Draytek Vigor 2900VG for accessing Sipgate, and find the
voice quality to UK PSTN is often poor ("breaking up" is the best I can
describe it).

I am set for G711A, with a packet size of 20ms. Would I do better with a
different packet size?

My broadband connection is by radio from a local supplier (Zycom) rather
than via BT. I don't know how it compares with BT on quality - but I
don't think that latency is a problem (20ms to 30ms for a ping to
www.bbc.co.uk), nor am I losing many packets (3% typical).

My router offers QoS, but I can't find any help on how to set that up
for Sipgate - would that help? And if so, can anyone suggest how to
configure it - I tracked down a previous post for QoS on 2900VG, - but
it suggests QoS settings that do match the options I am offered!

John Geddes
Derbyshire

John Geddes wrote:
> I'm using a Draytek Vigor 2900VG for accessing Sipgate, and find the
> voice quality to UK PSTN is often poor ("breaking up" is the best I can
> describe it).



> I am set for G711A, with a packet size of 20ms. Would I do better with a
> different packet size?

Larger packet size means less overall bandwidth.

But it also means that if you lose a packet, you lose more audio.


Unless you are touching the edge of your connection


> My broadband connection is by radio from a local supplier (Zycom) rather
> than via BT. I don't know how it compares with BT on quality - but I
> don't think that latency is a problem (20ms to 30ms for a ping to
> www.bbc.co.uk), nor am I losing many packets (3% typical).

Is that 3% packet loss when the link is in use or when it is idle?

If it is when idle, then it is loads of packet loss. I'd report it as
a fault.


If it is at the same time as you running bittorrent and a few downloads,
then it maybe isn't too bad.

What up speed and downspeed is the connection mean to do at?

> My router offers QoS, but I can't find any help on how to set that up
> for Sipgate - would that help? And if so, can anyone suggest how to
> configure it - I tracked down a previous post for QoS on 2900VG, - but
> it suggests QoS settings that do match the options I am offered!

The qos stuff will only help you prioritise traffic. So, if you web
browse and use voip at the same time, it will give priority to the voip.


If you are getting bad calls when there is no other traffic on the link,
then qos won't help at all.

My first step would be to check there are no viruses or worms on any of
your computers that are saturating your link and this causing the packet
loss.


Tim

Tim wrote:
>
> Is that 3% packet loss when the link is in use or when it is idle?

That was the result from each of two 100-sec pathping tests, to
different destinations. I've now tried with pingPlotter and get a fairly
steady 1% loss on idle, and 1% to 3% under load.

> What up speed and downspeed is the connection mean to do at?

2048 download, 256 upload - typically about 1500/240 in results from
adslguide.org.uk


> My first step would be to check there are no viruses or worms on any of
> your computers that are saturating your link and this causing the packet
> loss.
Thanks for prompting me to set up the "Syslog" on my router. Nothing
untoward (even with kids' PCs on) - with four PC's running but none
running any applications, RX rate is running 7 to 250 and TX rates are
11 to 300 - am I right in thinking that seems OK?


John Geddes