> - And by relying on Google Play Services, they avoid having to maintain a push notification infrastructure. It was mentioned in a sibling comment to GP, but

> - And by relying on Google Play Services, they avoid having to maintain a push notification infrastructure. It was mentioned in a sibling comment to GP, but Play Services are no longer required. If you don't have them installed, Signal will use its own push notification infrastructure. Indeed, this was not always possible, because they had to implement and maintain it first, in a way that would provide a good user experience for users. (And even then, the non-Play Services version is still somewhat detrimental to the user in the sense that their battery depletes more quickly, so it's a trade-off they'll have to make themselves now.)