Avísame works the same on iPhone and Android, so a family with both kinds of phone can share one Circle. Everyone gets the app, one person invites the others, and each person chooses what to share. You can check in with one tap, see each other on the map when sharing is on, and ask everyone for help with one Buzz. Free covers 2 people; alerts when someone arrives or leaves, and scheduled check-ins, come with Plus.
Questions
Can an iPhone and an Android phone be in the same Circle?
Yes. A Circle mixes both kinds of phone, and everyone sees the same things.
Do we each need to pay?
No. One Plus plan covers the whole Circle. Duo covers a Circle of 2.
Do I have to share my location?
No. Check-ins and Buzz work with location sharing off. You choose what each person sees.