On cellphones, no/C attestation can show up with "suspected spam". I believe T-Mobile does this today somehow, possibly a line under the caller ID.
Whether or not it's a premium service will probably depend on the carrier.
As for your original question (blocking), I'm not sure. It's certainly in the realm of possibilities and carriers' fraud departments will have to decide what to do with it.
Whether or not it's a premium service will probably depend on the carrier.
As for your original question (blocking), I'm not sure. It's certainly in the realm of possibilities and carriers' fraud departments will have to decide what to do with it.