I have a customer who has transmission problems at the distant end of a T1 that has voice and data traffic over it--They have an Avaya IP 500 and three 9608 IP sets--

There is an adtran in the circuit and a fortinet fire wall-then it is connected to a Cisco 208 SG switch to thr IP office--
They are having what they call waterfall noise or swishing sounds and also muffled transmission-

Various times during the day it gets worse--

My thoughts are they should have a Router that provides QoS that will prioritize voice and data --

Any help out there--I am not sure what the Fortinet can do if anyone might be familiar with that--I am going there on Monday and check the IP office settings - The IP is at the distant end 250 miles away and I will only have access to that over a tunnel

I would see if there is a way to put an analog or digital set on the system. Try to isolate if it is a trunks issue or an IP set issue....

Are you having this problem on all phones or just certain ones?
If all phones, I would definitely check QOS and if still no luck do as Matt ^^^ said and start the eliminating/troubleshooting process.

Thanks for the answer Matt. The three sets that having the problem are 9608 lp sets in Boston. The ip 500 unit is located in NY and runs over a T1 that has static ips. They are not having any issues In NY. The 9608s can work without a router that could provide QoS but I believe that this T provides Internet as well as the pipe for these sets, that is what makes me think that they need to add one. Is there any settings in the ip I should be looking for this type of muffling and clipping ?

QoS by itself will not necessarily cure the problem.
Your voice traffic is fighting with data traffic for bandwidth. The only sure cure is MPLS between the sites.

Forgot - If the T1 is point to point, QoS may be good enough to work without MPLS.