On Wednesday 01 November 2006 15:51, Bernie Borgmann wrote: > Don't discount the MTU, I have a DSL connection rated at 3000 down by > 800 up. And I get this, (as I am the ISP) BUT I still had voice chop on > the system default MTU for dsl is 1492 I had to drop it to 1440 at the > router (d-link). Now my pbx has excellent call quality and my network > is faster than before. Since the adjustment perfect.
Unless you're trunking with IAX2 or sending video you won't be running up against MTU issues with VOIP. The packets are *small* and *numerous*. Choppy audio can have a lot to do with the modem. I have seen the regular old shitty-ass modems that Bell supplies play silly bugger with your packets... they sometimes wait until a number of them have arrived before actually sending the data -- this leads to burstier data, which I imagine helps with their line coding, but is terrible for realtime applications. I *heartily* recommend the Sangoma S518 PCI ADSL modems. The queues are right in the Linux kernel and these things just work. I'm very happy with mine, and have installed a half dozen to various businesses for this very purpose. I'd also recommend some decent telco transient suppression since it's a pain to change out internal hardware. :-) -A.
