It's called 'caller id spoofing'. The people calling you can make any phone number show up on your caller id. They're making a number show up that charges you money if you call it and press a certain key.
At the same time they've disguised the messages on their pay by phone system as surveys. Those messages normally tell you what you're buying and how much it costs.
Check your bill for unwanted charges if you called this number back.
Just got call (after 9 am PT) and call lasted 15 seconds and hung up. We are on do not call list but do not know if this is an exempt call or just phony survey questions to evade law.