Read the forum guidelines
I have had calls drop, garbled with or without a headset, and have even purchased a new phone that is DECT 6.0. The base is in close proximity to the router (just replaced it also) and modem. The phone base is about 3 feet from the router and 5 feet from the Cox modem with two other handsets in the house. On calls, I constantly get drops, garbling, and told I sound like I am underwater. I have had Cox out here numerous times with no luck finding problem. I purchased a better headset, but even when not using it, I still have some problems. This issue is intermittent. I have Cox Hub in my backyard, so I am close to it. This happens on long distant calls the most, as that is the calls I am usually on. The problem is the same as with the previous phone and previous router. In addition, there are times that the Caller ID does not work and just displays 'incoming call'.
First, have you tried connecting the phone directly into the phone modem? Also, any problem with the internet?
I am experiencing this same issue. Just started within the last couple weeks. I thought it may be my phone but I replaced the phone and still have the issue. It's an intermittent problem, but very annoying.
Write down the times it happens and also do a speed test at that time!!