Carrier lock and IMEI blacklist are different problems. One limits which network can be used; the other can reflect a negative device record.
What carrier lock means
A carrier lock restricts a phone to a specific operator until the authorized unlock process is completed.
What blacklist means
A blacklist or block-list record can be associated with loss, theft, insurance, fraud, finance or administrative issues.
Why buyers confuse them
Both can appear as a network problem, but the cause and remedy are different.
How to check
Test the intended SIM, review operator information and check available device-status records.
Safe buying rule
Do not pay until the seller explains and resolves any restriction.
Frequently asked questions
Is carrier lock the same as blacklist?
No.
Can a carrier-locked phone be legitimate?
Yes. It may simply be tied to one network under contract terms.
Can a blacklisted phone work on Wi-Fi?
Often yes, because Wi-Fi is separate from cellular registration.
Can a phone be both carrier locked and blacklisted?
Yes.
What should a buyer do?
Verify both conditions separately.