I wouldn't want to be on your contact list. Feels like a betrayal of trust because they will most likely take their info and sell it to someone who will contact them through email/phone/social site/etc.
I thought about that... but then I realized they can use Mr. Number to block any spam!
I'm joking.
In their terms of service they say they do NOT do that. So,there's no betrayal.
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Again, the Caller ID part is SEPARATE from the Blocking part. The blocking part (calls/texts) is totally
free. You do not have to use the Caller ID feature if you do not wish.
If you do wish to use the caller ID feature, you can either pay for it or let your contacts be put in their database. So, there's TWO levels of opt in -- you have to say you want to use the Caller ID, then you have to say how you want to "pay" for it.
Ignoring the Caller ID feature, the Blocking features work well and you do not have to use anything else. Because users actively report spam calls/texts, you are protected from most spammers.
Here'a an example of a report:
http://mrnumber.com/1-800-594-2297
So, if this number tried to call you, Mr. Number would block it. With most other blocking apps, you have to manually add spam numbers.