/mcpcomplexity out of the call when you place a basic IP Phone to IP Phone or IP phone to PSTN call does the problem still exist? 4. If the call flow with the reported voice quality issue is complex, a UCCX call for example, does the user/phone experience the voice quality issue if they make/receive a basic call (both internal and external)? One User Experiencing Issues If the issue is with one User, work with her/him to determine these points: Step 1. Verify that the phone with the issue runs the same firmware as other known phones that work fine, if the firmware is different a firmware upgrade can resolve the issue. Step 2. Does the user experience the issue while she/he uses their handset, speakerphone, headset, all three? a. If the issue is with the handset only, verify the handset connections, if there is still an issue, swap out the handset with the handset from a different phone that has no reported issues, if the issue persists there can be an issue with the phone/phone firmware. b. If the issue is with the speakerphone try to adjust the volume, if issue persists, swap the phone with a known working phone, if the issue persists there can be an issue with the phone/phone firmware. c. If there is an issue with the headset verify that all connections between the phone and the headset (headset base), are other users with the same make/model of the headset without issue? If they are test a known headset that works fine with the phone with the reported issue, if there is no audio problem when you use the known headset that works fine the issue is likely with the headset and you can need to contact the headset manufacturer, if there is a problem with the known headset that works fine there can be a problem with the phone/phone firmware. Step 3. If the phone is on the same firmware as other phones without issues, and the user has issues with the headset, speakerphone, and headset the issue is likely to be with the physical phone itself or the network cabling from the phone to the switch. One way to test this would be to unplug the patch cable from back of the phone (as to not bring a potentially bad patch cable from the user's location to a test location), find a known working phone, and plug the patch cable from the working phone into the non-working phone and perform a test. If the audio issues are still present, there is likely an issue with the physical phone. If there are no audio issues, try replacing the patch cable (with a known working patch cable) that was plugged into the phone that experience issues, if it persists check the network cabling and all connections/punch downs between the users Ethernet jack and the switch. Multiple Users Experiencing Issues If the steps taken up until this point have not isolated the source of the poor voice quality the next step is to take packet captures along the network path that the RTP packets follow. Wireshark (or another tool capable to decode RTP streams) packet captures can help us narrow down the source of the issue with these steps. Step 1. Create a simple topology that shows the path that the RTP packets takes. This example uses this topology, the issue is that the customer on the PSTN side has audio quality issues when