Phones sound like cell phones (lost connection)

[Mitel33]

Hi All,

We recently change some Cisco switches from the model 29xx to the model 35xx, to gain more speed for our internet after that the phones are acting weird, when you talk from site to site sometimes the conversation cut off like if you were talking on a cell phone also voice mail is acting weird on the 2nd campus were we change the switches it play the voice mail slow and most of the time it cut off or you don’t understand what they say like if they are talking under water, when we change the switches we didn’t change nothing except the speed. Is there is something that I can do.

I use 2 3300 ICP Version 8.0.8.8 between locations and most of the information travels through the network I also have a T1 between points for emergency if the network goes down T1 suppose to pick up.
NuPoint Messenger MAS Adapter Release 11.0.5.7 Rev 01

Thank you,

 

[slapin]

Issue "terminal monitor" command on a Cisco switch where your phones are connected to and see if it will complain about spped, duplex and etc. Do you have computers connected to the beck of phones? Do you have phones in "voice" VLAN and trunk between sites? Do you have CoS configured on switches, do you have CoS options in DHCP settings? As you can see there is a whole bunch of things which may go wrong.

 

[Mitel33]

Phones were working fine until we change the switches. I have a mix we use VLAN for IP phones and everything is normal I did an upgrade from sx2000 to 3300 all the phones that I have are digitals only 15 phone VOIP there is a trunk or T1 between locations, I will check the terminal monitor on the Cisco switch.

 

[mitelmitel]

This is a definitive QoS problem.

Make sure that every port on your cisco switches are configured for Vlans.

 

[AH64Armament]

Is your T1 router configured properly for QoS? Can you monitor it and see packets that are marked? We use Adtran routers, and we are able to see this in near real time.

I agree with prior post... check the switch to see if any switch ports are complaining of duplex mismatch or any thing else.

Are you using Spanning Tree? If so, what is the master? You MUST have a master switch with Spanning tree, to do so on HP switches enable one by using the command "spanning-tree Priority 0". Only do this on ONE switch. All others just enable spanning tree.
Without having a master, the switches will negotiate for master all the time.

Also links between switches and the phone system should have flow control enabled.

Is the switch set up to use VLAN Priority? Is this the same VLAN priority in the Mitel phones?
Mitel likes to have the phones set for VLAN Priority 6, whereas Cisco likes to have set as 5.

 

[Mitel33]

I was talking with the network admin and he's monitoring the network but he also mention QoS, we will look on all the recomendations, thank you.