why is my husbands phone ringing when mine is called?
It is called continuity. You can disable this by going into Settings -> Handoff & Suggested apps and disabling it.
Or by going into Settings -> Facebook -> Disable iPhone cellular calls.
It seems you two are sharing one Apple ID. I suggest creating individual IDs and just turning on Family Sharing. This will allow you to share your purchases without having to share one ID.
With Apple creating Family Sharing there is no longer a reason to share a single Apple ID. Everyone, including kids can have their own Apple ID without fear of them making unwanted purchasing, and you can all share apps, movies, books, etc. that are purchased on any account. It can all be linked to one credit card as well.
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