Resolved "Unable to create a power assertion" - FaceTime calls failing to connect from Mac

[maverick28]

The topic is based on an accidental discovery of mine regarding the seemingly persistent inability of the desktop counterpart of FaceTime to pass the connectivity wall of the mobile one. When the call is initiated Console, among others, contains the entry

Unable to create the power assertion for "ActiveFaceTimeConferenceAssertion"

The entry pinpoints the source of the misbehaviour which is those settings of the iOS device that are responsible for power management, namely in the section Do Not Disturb: the settings in question are Silence repeated calls from the same person, Silence calls when the screen is locked. When the iOS device goes into sleep mode its screen locks automatically after some preprogrammed amount of time. If you go to Settings-->Do Not Disturb-->Silence you'll see that Apple left only 2 options to choose from: "Always" and "When the screen is locked". There's no "Never". To figure out how to deal with that and as a partial solution you have to disable Auto-lock which is possible only if you turn off Low Power Mode and set Auto-lock to Never. However, when your iPhone enters standby mode it still locks itself.
With iPhone locked when FT from a Mavericks machine tries to reach its mobile counterpart, it simply can't because it's unable to "create the power assertion" - something like the caffeinate (10.9 and later) or pmset (every macOS) command utilities do on the desktop: with them, you can wake the Mac, turn on/off the display, system or disk at any designated time - "create a power assertion". In the case of FaceTime, your Mavericks machine should be capable of performing the same action but it isn't. If you unlock your iPhone and immediately call then the call reaches it. If it locks back the call is dropped.

NB. They fixed the bug in newer versions, and as of High Sierra and Mojave - 2 macOSes I've used personally - calls from the desktop FaceTime are able to break through the locked state of the iPhone.


The problematic settings

NB. It seems iOS 13 presented a new case where incompatibility between it and Mavericks introduced new connectivity shortcomings. The assumptions from above pertained to iOS 12 that I still use and may not apply to the full extent in regard to iOS 13.

NB Video calls between Mavericks and iOS as new as version 12 halt when the recipient answers the call on iOS, audio calls produce clearly audible echo and artificial background noise which are unfixable.

 

[Wowfunhappy]

Interesting! So, to summarize, your theory is that Facetime calls placed from Mavericks are unable to properly wake up the receiving iPhone? That would be totally nuts, although I suppose I've seen stranger things.

I have to say though, outgoing Facetime calls continue to work fine for me, although it's possible everyone I've called has had their phone unlocked. I usually message people before calling them.

 

[maverick28]

To summarize, your theory is that Facetime calls placed from Mavericks are unable to properly wake up the receiving iPhone?

Exactly. With iOS 12 I tested by calling myself. However, calling a iOS 13 device from Mavericks is not possible at all. Verified personally by trying to call another person running iOS 13.7. The call comes through randomly and rarely but most of the time it doesn't.
It would be interesting to know whether that's a compatibility regression that cropped up recently or it was inherent in every earlier iOS (6-11).
I, however, discovered smth so complex and hardly predictable that even describing it poses an issue of its own. It might have something to do with AddressBook (a.k.a. Contacts) in Mavericks from which FT acquires its contacts. I have several instances of my own contact card across several accounts containing my number to which I assigned the "iPhone" label. During my experiments with calling myself, if in FaceTime or Contacts I choose one instance of it the call comes through. If another, it drops. In the case of video-calls, when I send a call from Mavericks to my iOS 12 device:

• If I choose one instance to call from FT contacts and the call reaches the iPhone, the connection fails as soon as I tap "Accept"
• If I choose another instance in the same scenario the connection succeeds albeit sound artefacts are jarringly bad.

I added successful instances of my own card to Favourites but this isn't a solution since I don't know why those were good, in the first place, and how would that play out with other contacts.

 

[Wowfunhappy]

However, calling a iOS 13 device from Mavericks is not possible at all. Verified personally by trying to call another person running iOS 13.7. The call comes through randomly and rarely but most of the time it doesn't.

I have successfully placed calls from Mavericks to people who I know were running iOS 13. And iOS 14, more recently.

To be quite honest, I think I've had less Facetime weirdness since I downgraded to Mavericks in March. On High Sierra, I'd sometimes have to restart calls a couple times before they would ring for the other person.

I'm perplexed, to say the least.