Troubleshooting choppy, garbled and out of sync audio issues in your DECT network can be a difficult task. Incorrect arrangement of the DECT base stations in a multicell is a known reason for many isues inclusing audio.
The M85/M65 and M25 handsets have a diagnostic menu that helps to determine if there is a weak or inadequate RF/RSSI signal between the handset and the M700 or M300 Base unit.
Checking multicell DECT sync source values
If you are using several base stations in a multicell, make sure that they are arranged correctly. Click on Multi Cell -> scroll down to Base Station Group to see the list of bases. The table will look similar to the one below. Check under "DECT sync source" and make sure that none of the values are below -75dB. In the below example, value -86dB is too low and can cause audio issues. If you have any such value, re-assess the arangement of the base stations (see https://helpdesk.snom.com/support/solutions/articles/6000167180-how-to-properly-deploy-a-dect-multicell-system). You may need to add some additional base stations.
Checking RSSI signal level
If you are experiencing audio issues you should check the RF/RSSI converage in the areas where you are experiencing the problems. First check the RSSI signal levels between the base stations and he handsets.
1. On the M65/M85, press the menu key ; on the M25, press the OK key . The main menu is shown on-screen.
Audio Loopback Testing
You can also do audio loopback testing to see if the RF signal in those locations your have tested from is a contributing factor of the audio issues.
The Site survey mode can help to check handover/roaming scenarios and can give a more complete picture of the DECT conditions on-site (see https://helpdesk.snom.com/support/solutions/articles/6000167180-how-to-properly-deploy-a-dect-multicell-system -> Site Survey). Interference due to reflections should be easier to find with this function (error counter: FE). Also, an inconsistent multicell could be detected.
Checking the multicell page can show problems in the DECT tree which must be corrected in order to stay within the recommended values (-75db or more).
Try performing the RSSI and Loopback tests on the affected handsets when the issue occurs and keep a log of the RSS levels and loopback results for Snom Support if you open a ticket. If coverage and RSSI is an issue, adding DECT repeaters to extend converge in your Network may be necessary.