when your mobile telephone rings & you have no idea who the caller is you can answer it by saying - hello,
You could screen your calls by not answering, however I ain't going to leave voice mail messages in a mail box which doesn't state who it belongs too.
Should you ring back at some point I have no idea who you are unless you give me at least a hint of your name & address
I've not saved your details into the handset, I answer every call (unless blocked) with hello,
I could not give a shinny shit whether your job gets repaired or not.