If you don't want to spend the money on the Autocom bluetooth dongle another choice is an older Motorola bluetooth speaker/microphone, the HF820. These are probably only available on Ebay now. The Motorola adaptor has a 3.5mm headset jack on the side that can be patch corded into the Aux input on the Autocom. This becomes your audio link to the Autocom by pairing the Motorola adapter to your phone via bluetooth, then pair the Zumo to the Motorola adapter to give the "onscreen" readout of what's happening with the phone. Details below are copied from the Zumo forum.
I get asked this so much by PM I thought I'd post a final soliution to making this combination work. As most of you know, Autocom's Zumo lead does not work properly (see below).
In order to make the Zumo work properly with an Autocom, you have to split the music from the phone signal. If you don't do that, the Autocom can't handle it.
The Autocom treats music as lowest priority and the phone as highest priority, but the music & phone signal from the Zumo comes combined from the same socket. If you leave the signal combined, then you have to tell the Autocom it's either all music or all phone, which causes problems.
If you say it's all phone (Aux 1) then you only get mono music (Aux 1 even on the latest Autocoms is mono only) and it stays at 100% volume all the time, even when you speak to a pillion or on a bike-bike radio as Aux1 has top priority. If you treat it all as music (aux 2) as Autocom's official lead does, then it will cut the audio to 50% when you are on the phone, so you can't hear the caller and if you use a bike-bike radio, that will take priority over the phone call so the radio will come over the phone call at 100% volume and reduce the phone call to 50% volume.
So, you have to split the music and phone signal from the Zumo and the only way to do that is via Bluetooth.
You must get a Bluetooth headset dongle and plug it into Aux 1 on the Autocom. Then you pair the Zumo to the dongle.
Next you connect the standard 3.5mm music lead from the Zumo to Aux 2 on the Autocom via an isolated music lead. It usually has to be isolated as both the Zumo and the Autocom are bike powered, so other wise you'll get a crackling in the speakers known as ground loop interference.
Wired this way, music is sent to Aux2 and reduced to 50% when you are talking, but the phone calls are sent to Aux1 via Bluetooth and always take priority over everything else at 100% volume - thus it all works perfectly as it should.
The good news is that you donít have to pay Autocom prices for this stuff. Here is a link to a Motorola HF820 dongle on eBay that can be yours including a 12v charger and delivery for under £15. This dongle can easily be connected to your Autocom using the 2.5mm to 3.5mm phone lead they supply with the unit. It'll just plug in and pair with the Zumo, no messing about necessary.
You can also use a Sony HBH-200, which also works but is a little harder to find and a few quid more expensive.
And here is a link to getting a cheap isolating music lead for £6.50:
SHORT LINK TO EBAY