This appears to be a quirk of how iOS is communicating with Bluetooth speakers.
If you are initiating the call from your phone, the audio will default to the internal earpiece of the phone. You can tap the Audio button, then select SoundLink Revolve to ensure audio is output directly to the speaker.
If you want the audio to output directly from the speaker from the get-go, you can press and hold the multi-function button on the speaker to invoke Siri, say "call [name]" and it will begin calling with the speaker as the audio output. I believe this may be due to recent changes made in iOS 13 which separates some audible entities with Bluetooth (including notifications no longer being heard from the speaker.)
In the past, I was able to default the audio to the Bluetooth speaker by going into the iPhone's accessibility settings > Call Audio Routing, but changing this appears to not make a difference now on iOS 13.
Hi Jeff, thanks for the explanation. Like you, I have concluded that it is a compatibility issue between IOS and the Revolve+.
The same phone and my Bose QC35 gen 2 doesnt have this issue, which leads me to suspect that it is likely that its a soundlink firmware rather than an IOS firmware issue. Everytime a make a call it momentarily tries to route to the Revolve Speaker (Default already set on the iPhone) but seems to be rejected and then routes to the internal speaker.
Thanks for the suggestion re: Siri or manually selecting the speaker. The main reason that I bought the speaker was so that I do not need to hold the handset everytime I make a call. Incidentally, I spend approximately 2,500 plus minutes a month on my mobile and make 30-40 calls a day. Not everyone I call is in my phonebook, so using siri is an option but not the solution. Manually changing to the speaker everytime isnt the solution either. Bose fixing the firmware would be the solution.
I scratch my head because a 10 year old UE miniboom can work reliably (fraction of the price) but a brand new $NZ 450 Bose speaker cannot...
Looks like I now sit with a handy Bose paperweight for my desk. Looks like I Will have to move to another brand that can do the job. A real pity because I used to have huge confidence in Bose products but this experience, coupled with a disappointment with another Bose product is exceptionally disappointing. A waste of time and money.
Interesting that Bose / Sales agent didnt mention the issue when purchasing the product, even though I specifically mentioned that I would be using the call routing functionality.
Jun 15, 2018
I may have been the one that was involved in that other thread. As I recollect, the problem is with ALL Bose speakers (I have two Revolves and one Mini 2) and NONE of the Bose headsets (I have a QC35ii and a Soundsport). It kept going back to the phone speaker and I had to switch it back TWICE before it would finally stick. I tried for months unsucessfully to convey that this was a Bose speaker issue with IOS and was not specific even to the Revolve. No one in Bose seemed to be interested in fixing the firmware and Apple had no interest because the issue was Bose specific.
I eventually gave up and stopped making and receiving phone calls with the Revolve. I now do it exclusively with my QC35ii.