Fix Google Voice Not Ringing Hangouts App on iPhone (iOS Hangouts App)
Google Hangouts will let you receive calls, texts and voicemail from your Google Voice number. In theory, this works on the iPhone (iOS) app as well. It appears like it would be really easy to set this up. There's just one setting that says "incoming call ring" that looks like all you have to do is toggle that setting. Wrong! There's yet another, more hidden setting that many seem to be struggling with and I can see why. It really is not intuitive to find this 2nd aka "hidden" setting that you have to switch on to be able to receive your Google Voice calls on the Hangouts app. I was banging my head against this for the better part of a week until I just happened to stumble on the fix. I searched high and low for some kind of tutorial, answers in the Google Support forums - anywhere! There were some mentions of a second setting but those were mostly for Android users and of course there were no screenshots which made it even harder to find. Upon changing this setting, it was instantly fixed! Now I can get calls from any phone that calls my Google Voice number via Google Hangouts App on my iPhone. So basically I have completely free calls to the US and back while traveling by using the Hangouts App on my phone.
Here's the steps on how to fix Hangouts App not ringing Google Voice calls
Okay, well it's more like how to enable it. But since it's such a poor UI that people can't figure this out due to the redundancy of the terminology used, I think "fix" is a fairly descriptive term. :) For what it's worth, the instructions from Google are here. They are accurate, but it didn't dawn on me until I found the second "Incoming Phone Calls" setting and referred back to it. Note: The blacked out parts are my Google Voice number, and the circled red parts are what you need to click on to change the settings. Click the screenshots to enlarge them if you need to.
Step 1: Enable Incoming Call Ring - First Setting
The first step is to enable the main "incoming call ring" setting. This setting allows for Hangouts calls (as opposed to phone calls) to ring on the Hangouts app. This is where the confusion lies, because by looking at this setting it appears like you have it set to ring, and when you have the setting within hangouts on desktop to ring your Google Voice number as well, it makes you think you have it set correctly. HOWEVER. The setting to ring your Google Voice number in Hangouts appears to be per-device (aka one for desktop/web and the other for iOS App)
Step 2: Find your Google Voice Number in Hangouts App
All you have to do is scroll down the settings in the Hangouts App and you should see your Google Voice number. See the screenshot on the right to see what I mean. Remember that my phone number is blacked out, so you should see your phone number listed there in a (555) 555-1234 format. Click the arrow on the right to enter the settings page for your Google Voice number.
Step 3: Enable Incoming Phone Calls for your Google Voice Number
This should be the last step. If it does not work after this, you may not have the settings within hangouts on the web and Google Voice correct. You can see instructions for those steps here. Once you are on this page, all you have to do is toggle the "Incoming Phone Calls" setting to on. Optionally you can also do this for voicemails and text messages as well, if you want to. Now go test that your Hangouts App is ringing when you are called on your Google Voice number. If you don't have a spare phone around, or have some other reason you can't call your Google Voice number, you can try a service like this, which is what I used.