I just purchased a big Jambox and for the most part, I love it. The speaker phone is awesome and almost makes the $269 price from Amazon worth it, but one thing was just driving me crazy.
When I plugged the JamBox into my Mac running Windows under BootCamp, the computer took priority over the Bluetooth connection between the speaker and the iPhone, and VoiceOver on the iPhone stopped talking through JamBox.
In fact, the iPhone stopped talking at all, since the PC-JamBox connection completely overrode the Bluetooth connection established by the iPhone, and VoiceOver on the phone wouldn't even come out of the phone's little speaker, making the phone impossible to use as long as the computer was plugged into the JamBox.
The speaker phone still worked perfectly, so even though I couldn't use VoiceOver on the phone, the speaker-phone was activated automatically when a call came in, even though the computer was still connected to the speaker. So, that part was really cool.
However, I still needed to solve the problem of not being able to use VoiceOver on the phone while it maintained a Bluetooth connection with the speaker whenever the speaker was connected to the computer.
Through some good luck, I got the next best thing to work. Even though the PC connection to the speaker silenced the Bluetooth connection (except for phone calls), the phone is smart enough (thank you Apple) to route VoiceOver on the phone to a headset if it is plugged in to the iPhone.
So now, I simply have the phone on my desk with a headphone plugged into it. When I want to use voiceOver on the phone, I simply put on the headphones and all is well. Both the computer and speaker-phone work great through the JamBox, and the phone talks just fine through the headphones.
I still wish that Jawbone would aford VoiceOver on the phone the same priority it gives to incoming calls, thus allowing VoiceOver to speak through the speaker while a computer is connected, but even if that never happens, my trusty headphones will give me full access to the phone.
If someone has a better idea, write me at firstname.lastname@example.org
The Down Side to my Solution
I neglected to mention that with the headphones attached to the iPhone, one misses any notifications of calendar alerts, emails, text messages, or any other notifications one has set.
This can be mitigated by using a small speaker instead of a headphone. Thanks to Jessica Brown for that suggestion.