The problem of widespread caller ID spoofing is still a relatively new problem. While telemarketers are restricted by the Do Not Call List, scammers don't have to worry about such things, and spoofing is a serious problem. Ars Technica recently talked about the issue at length
US consumers receive 2.4 billion robocalls a month, and the ones from spoofed numbers are among the hardest to stop, according to the Federal Communications Commission. Recognizing that today's robocall blocking systems are often useless against spoofed robocalls, the FCC recently called upon carriers to increase their efforts to block them.
What's really scary is that there's not much the government can do to stop the problem
Because it's an old, circuit-switched network, none of the switches along the way need to know who actually is placing the call. I was shocked to find out that the Caller ID is just an optional part of the original address message that gets sent along. You don't need it, and nobody is checking it along the way for authenticity, and, really this means you can put that to be whatever you want. To top it off, there are a lot of online services that allow you to send out phone calls and specify exactly what Caller ID you want them to come from.
It looks like the FCC is going to relax some rules, in the meantime, to help at least start to curb the problem
FCC Chairman Ajit Pai has proposed rules that would let carriers block calls in cases when the spoofed Caller ID can't possibly be valid. This includes numbers that aren't valid under the North American Numbering Plan, valid numbers that haven't been allocated to any phone company, and valid numbers that have been allocated to a phone company but haven't been assigned to a subscriber.
At present, it doesn't look like Congress is going to deal with this.