4

I'm using Samsung Galaxy S5. There is an icon which looks like a house with 2 waves in the notification bar, in between (and slightly above) the 4G and mobile signal strength icons.

Here's the screenshot
Screenshot
Click to enlarge

I only saw it once and never again. I was reading text messages.

5

The small house icon is an indicator that you're connected to a Verizon Network Extender.

Screenshot
Click to enlarge source:androidcentral

They are primarily used for people that want to have Verizon Wireless service in their house, but there is no or very little network coverage in their area. They purchase the Network Extenders that hook up to their broadband connection and provide coverage for them. Someone in around you might have one of these extenders.
Source

Dialing #48 will give you a recording telling you if you're connected to a Network Extender.

Here's a picture of Network Extender

Network extender device
Click to enlarge

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