To know if your phone is connected via the Network Extender, you will hear a short double tone at the beginning of your call. Note that if you're in an area with excellent coverage already, having the network extender probably won't boost your call quality all that much. Also, the network extender only works for voice reception; if your house doesn't get 3G or EV-DO, you're still out of luck.
For more advanced use, you can set your Network Extender for open or managed access. Open access means you're letting any Verizon phone within range, even your neighbor's phones, use your Network Extender. Managed access means you get to prioritize access for up to 50 Verizon Wireless callers that you select. Everyone still gets access to the Network Extender for those emergency 911 calls.
We're pleased with the unit overall, and it's certainly useful if you're a Verizon Wireless customer in an area with poor coverage. Even though it's expensive, at least you don't have to pay the monthly service fee that the Sprint Airave requires.