There seems to be a big difference of opinion over whether you pair:
1) phone to NavIV, NavIV to headset, bike to headset, or
2) phone to headset, bike to headset.
Not quite sure how the nav audible messages get to the user in case 2 but I presume that they go through the bike audio? There was mention of "hard-wired" in a previous post but I wasn't completely clear what that referred to.
I only mention these options as reading through the forum, people tend to assume that the way they have set up pairing is "the best" and a reader not knowing about the options might be misled, and especially as the BMW manuals seem to imply method 1 which might cause confusion. Personally, I use method 1 (with a Sena SMH10, latest firmware) but that's because I'm used to operating the phone via the GPS screen - although this was easier on my Pan than on the 1600 as the screen was nearer!
Anyway, I'm having a lot of problems at the moment that I thought might be down to things like the order in which pairing is done. After some experimentation, I have found that it seems to be a Bluetooth problem on my Android phone (Galaxy S2, Android 4.1.2). It pairs with the NavIV with no problem, but as soon as I get or make a call, the audio connection disappears. If I use the phone to switch call settings back to phone rather than headset, then back to headset again, the audio connection is remade and it seems to then work - at least for that call. This seems to be a well-known problem with recent Android releases and on more than just the Galaxy. My question, after all this build-up, is whether anyone else has seen this problem when using an Android phone paired directly to the Sena, and if not, this might be a workaround for me.
And no, swapping to an iPhone is not an option as that comes with its very own set of problems!
And if I'm honest, this isn't really a "1600" problem anyway as the bike isn't involved in any of this. I'm really just canvassing views from SMH10/Android phone users as there seems to be a number of them here.