Who calls using only four digits showing on four numbers on caller id?

Answer 1

It could be someone from a foreign country, but most likely it is an unscrupulous telemarketer.

If you operate your own PBX or you use an IP (internet) phone service that has lax security standards, you can spoof caller id (make up your own caller id). This is commonly done by certain telemarketers or sometimes other people who want to hide their identity when calling. Do not do business with telemarketers who are trying to hide their identity -- they are hiding their identity for a reason. Better yet, never do business with any telemarketer.