[Asterisk-Users] MTU and Voice Delay (latency??)

[Geoff Manning]

Our users are experiencing some unacceptable delay when trying to have a
conversation. The delay is so noticeable that they keep stepping on each
others words and resort to calling the customers via cell phone.

Here is the setup

SDSL Connection (PPPoA)
Speedtouch 610 SDSL Modem
3Com 2224PWR Plus Switch (phones on separate VLAN)
8 Cisco 796 Phones

All connecting to a remote Asterisk Server.

We found that the MTU for the SDSL modem was set to 1500 and I have since
changed it to 1458 which is the ISP's recommended setting.

Can this MTU difference cause the delay my users are experiencing? All the
voice packets would become fragmented so it sounds logical.

And simply changing the MTU on the modem, will that fix it, I can't find a
way to change it at the Cisco phone level.

Thanks,
Geoff Manning