Thanks @Rahul_Wankhade for the details, but it could be any number of things. Is a case open with Meraki Support to start digging into your wireless configuration, confirm the right settings, best practices are being followed, 802.11r status, minimum bit rates, band steering, etc? Was a pre-deployment site survey completed, or at least some type of VoIP readiness assessment and config review completed? The -50 dBm might be great, or might not be, also depends on a few variables and your specific RF environment, but hopefully you have a continuous -67 dBm throughout the environment. Check that any/all QoS configs are set up properly, on the wired side too. Run latency tests and make sure things are within range, etc. Try to collect whatever data points you can and mention all of them when opening a case. Did you come up with a channel plan based on the 8821? Are you band steering to 5GHz? Do you have DFS channels enabled, and if so, confirmed if and which of those channels are running in your deployment versus what the phones support, and if there's a mismatch, tried disabling DFS channels to re-test? Have you tried a newer firmware with as the latest GA 26.8.1 and/or reviewed the corresponding release notes between your 25.13 and 26.8? Sorry lots of questions, just throwing out some thoughts on things to consider or perform in conjunction with opening a case.
