[asterisk-users] Diagnosing poor call quality

Ed W lists at wildgooses.com
Thu Feb 8 03:37:05 MST 2007


Check from the sites in question using "testmyvoip.com" or whatever the 
site is called.

In the UK I found that some strange things sometimes happen.  At one 
point I was sure that BT were perhaps misclassifying IAX packets as 
P2P... However, not had a problem with SIP.

Beware that ADSL uses vastly more bandwidth than you expect on small 
packets, eg if you are classifying using a cheap router then you 
probably need to at least half your claimed bandwidth in order to make 
the prioritisation work correctly.  I added some (hack) patches to fix 
the linux calculation for HTB on the linux QOS list a year or two back.  
If you have a linux router you could use those to improve the 
calculation quality for QOS - or else I found a Draytek router does 
impressively well at getting it right for small sites...

Very likely you will find that the issue is variable jitter on the 
line.  The link above should help you figure this out

Good luck

Ed W


More information about the asterisk-users mailing list