I came across Hamshack Hotline recently. This is a Voice over IP phone, the kind you can add to your internet, with a service provided free to hams.
You buy an older Cisco VoIP phone and you can then provision it with their network and connect to your internet.
It’s not over the air, so non-ham family members can use it.
While ham radio is looked at as a backup and for emergency use there are many situations where your local cell tower is down but your internet remains up. As a large percentage of people have got ride of their conventional phones this does provide a cheap backup to your cell phone. The cost of a suitable phone is under $100.
For MAG’s this can provide an additional level of communications as you can set up group numbers or calls from what I’ve looked at.
In addition to VoIP hams can set up a mesh network, a wide area wifi, using off the shelf 802.11b and g routers. They operate just outside the 2.4GHz and 3.4GHz ham bands and can be easily modified to work in the ham bands. With a ham license you can operate the devices at a higher power and create links between nodes of up to 10 miles. For more information see the family communications plan article.
You should certainly consider these as an additional layer of communications in your family communications plan.