Does anyone provide spam call blocking for randomized numbers identified as "Unknown" or "Suspected Spam"?

Currently your best defense is a phone with a good call blocker or a third party blocking device. They do a much better job than any of the current phone company tools, any phone company. The possible spam message is one of the things required by the FCC that the phone companies must put out for digital or cell service.

None of the cell carriers actually block SPAM calls.  Seems odd that if they can identify a caller as potential SPAM but apparently the technology is just too vexing for ATT to implement.  About the only thing that will block them is to set your phone to "block unknown callers" and let the calls go to voicemail.  Chances are they will leave voicemail.  But, if you're doing business with people that call from unknown phone numbers, you would obviously run the risk of not receiving calls that you want.  This is such a ridiculous situation that the carriers allow to happen.  Thanks FCC

@dspindler I don't know about AT&T, but some carriers do block known spam it's the it's the unknown ones that look suspicious that get the "possible spam" tag. Here's some of the things the FCC has been doing, not all are implemented yet. Right now the phone companies aren't allowed to block unknown callers, but you can do it yourself if you have a phone or third party device that will do it. 

It's unfortunate our carriers are not allowed to block unknown callers, but it, perhaps, explains why the tools available are not very effective blocking spam.  I assume that is the reason Call Protect does not block flagged numbers.  My current Call Manager log shows 585 calls, of which 148 were flagged and 32 auto blocked.  Whether it be due to the complexities of technology or regulations, it is obvious the end users will have to rely on third party hardware or applications.

Thanks for your input, I am now much better informed.

I have been rather disappointed in the AT&T call screening. A few days ago I got a call on my mobile that was flagged as likely spam, but the number looked familiar, although it wasn't in my contacts. I answered it, and sure enough, it was a call I had been expecting from someone I needed to hear from. I'm guessing the screening technology is too unreliable to make actual blocking a good idea.

It's not the carrier's that initiate the "likely spam" display, its other people, like you, who report it as likely spam. Read this. Seems you want to blame everything on the carrier, and it isn't always the carrier who's to blame. Also, you said on your mobile phone, this is a home phone forum. Since this is the home phone forum, I'll repeat what I've said many times. A phone with a good call blocker or third party blocking device is better than anything provided by the phone companies, mainly because you can block or screen things the phone companies can't.