"this accessory is not optimized for this iphone"

Check your docking port for debris or bent pins.

I've been having this problem to and I have no volume on anything it says no volume available I had an appointment with the apple people and they told me to reset my phone and that didn't work and I still havnt been able to fix it

I've been having this problem to and I have no sound on any thing everything says no volume available I had an app. With the apple people they told me to reset my phone and it didn't work and I still havnt been able to get it fixed

I am in Alberta, Canada and I am having the same problem. Help!!!

Same problem with iPhone 4. Any solution?

Hi, I have the same problem and I can't solve it and it's soooo annoying!

I'm having same problem, no volume getting same message , pins in port are straight , rebooted and did everything possible this is very annoying. Help! i will be bringing it it on Tuesday for the techs to looking to it

I also have the same problem. Yesterday, I just upgraded to OS 4.1. So far, I noticed a lot of fixes including this problem, faster start-up of camera, no more loss of sound, etc. I hope it lasts.

I had the same problem with my iPhone 4. Message would pop up every half hour or so. After message, external audio was disabled. Tried restarting phone, but as soon as message would pop up, external audio was once again disabled. Tried using can of compressed air to blow out dock port, but no luck. Then, gently used a toothpick to remove lint in dock port that air can wasn't strong enough to blow out. Worked like a charm. No more message and external speaker is working fine again.

The main conclusion drawn is that the OS upgrade to 4.1 has cocked up output to audio/video. There's loads of topics raised concerning people's individual car stereos that were previously compatible with their iPhones.

The real bummer for me is that in August I went specifically to an Apple Store to test and then buy the proper AV composite cable so I could output video to a TV. It worked right up until the moment the new iPhone OS was installed.

NAILED IT!!
its not a software problem so ignore what they tell you in the store.
i docked my iphone into my alesis p.a system (if any one has ever tried to dock one into one of these then you'll know how difficult it is) and its disturbed the male side of the USB input inside of the phone. all i did was put my credit card into the bottom of the iphone and slide it down a few times. works perfectly!!

I've tried everything mentioned and still I've no audio on my Sony Alarm clock, could you elaborate on the credit card method more Mikey

Finally found a solution to this. I tried everything and finally used the corner of an envelope to clean the bottom slot on the iPhone, similar to what Mikey did with his credit card.
There's a slim gap that's too hard even for a toothpick to get into to clean. You'll need to clean in there and I got mine working this way.

i had the same problem..and here's how i solved...Made your self a passcode lock..then when it will ask the code...input it wrong till the phone is locked for 1 minute...after is unlock again just input the right code...thats how it worked for me...hope it will work on you.....(and just to know that's how i got the problem in the first place...i get it wrong..and afterworlds a was getting that pop up)