We do the same and have had ever since caller ID. Now we have NoMoRobo on all our lines and I watch incoming calls very carefully. But the Dish Network number is a known number that has called in the past and was valid. So to say not to answer unknown calls that's great but this is a known call.
The latest in new scams is number spoofing including caller ID information that makes it all the more difficult to figure out who's calling, so you may just very well pick up an unknown call with a spoofed number.
Nowadays, unless it's a number that we get called from often and really know who it is, we let everything go to voicemail and screen that. So if it is a legitimate call they'll leave a message and will call them right back. That is if NoMoRobo doesn't catch the call before it gets to us.