I have the same Panasonic system and the same problem.
I've made a few calls that sound fine but _often_ when I get an incoming call, I have to excuse myself and go pick up the call on the iPhone. Callers complain that I sound very garbled.
I've reset everything and re-established the Bluetooth connection to no avail. It doesn't seem to matter whether the iPhone is next to the base station or in the next room.
Amazon customers' reviews of this combo are goot-to-excellent, but most don't mention which model iPhone they have.
(It's cool that the Panasonic phones ring with the iPhone's custom ringtones.)
iPhone 4S, Panasonic KX-TG7645M (the '5' is the number of handsets)
Well I couldn't take it anymore and switched my phone service from the iPhone back to my trusty blackberry utility. I must be one of the only people on the planet to switch from an iPhone back to a Blackberry but I work from home and don't have a seperate telephone line just the cell phone so the compatibility between cell and bluetooth house phone is critical. Very disappointed that I had to do this and hope Apple comes up with a fix as I would switch back in a second.
I have the same issues with my iPhone 4S and the Panasonic system. All my callers say I sound very garbled or I must be talking "under water". My older iPhone and Motorola cell phone worked fine on he Panasonic KX-TG645. I'm very disappointed that Apple has not addressed this issue and find it inexcusable.
We have the Panasonic KX-TG7745, the newest incarnation of this Link to Cell device. Same problem as the OP, although in our case, we have 2 iPhone 4s in the home and one iPhone 4. The signal is perfectly clear on the iPhone 4, no issues. On the 4S's, however, the caller almost always says I sound garbled and typically hangs up because they can't understand me at all. It doesn't matter if I initate the call or answer it....just get that same "Cant understand a word you are saying." I've called an outside line and left myself a lengthy voice message so I could check it myself and sure enough its almost unitelligible.
Using the same recording trick, however, I've also done this at times wher I've had ZERO voice garbling. The 4S was sitting in the same spot (on its charger), nothing else in the house changed (no lights on/off, microwave running, AC/Heater running...everything the same).
So it seems to be a software or environmental glitch. I can't isolate it and have been trying to do so now for weeks to no avail. Anxious to find a fix or I'll have to resort back to a normal phone system.
Still the same problem here. I don't use it as my primary means to make or get phone calls, so it's tolerable but disappointing.
An iPhone 4 works okay, and so does my wife's some-other-brand cellphone. Unlimited calling on the landline means that I'm not using the iPhone/Panasonic link to originate calls.
If/when I receive a call on the iPhone while at home, the Panasonic is basically a means to ring phones around the house (and announce the Caller-ID). Then I go pick up the iPhone to talk to the caller.
I am running into the exact same problem, but with the KX-TG7745s. I've been on the phone with Panasonic, and they insist the iPhone 4s is compatitble.
They had me power cycle the unit, reset network settings on the iPhone, and even disconnect the landline cord. Nothing solved the problem. My girlfriend is getting sick of me calling her to test it out.
I asked the tech support person if a different model might work. She said the 7700 series is new for 2012 and the 7600 series or anything older wouldn't be any better. She suggested I return this unit and exchange it for another- but I don't believe it's just this unit that is defective.
I'm actually inclined to believe it's not a Panasonic issue. (other than they call it compatible) I think Apple did some funky things with their bluettoth on this phone. The iPhone 4s is also not totally compatible with my Toyota Entune system. With an iPhone you have to plug in the cable to access features. With any other phone, everything is done via bluetooth.
Does anyone have a recommendation for a BT handset that actually pairs with the 4S? I have an old GE Fusion Cell model that worked perfect with the Iphone 4 but when I got the 4S it has the same issues as mentioned above. I would like to buy one that actually works, It sounds like Panasonic is out of the question. appreciate any recommendations.