1. Further action: This means it will sit on the bill collector's desk until the end of the month when it is shuffled to another bill collector.
2. Immediate Action: This means they'll call you again tomorrow.
3. Out of my hands/No more chances/About to transpire/(something similar): This means...absolutely nothing.
4. Mentioning anything about your license/social security number/your work/payroll: This means...absolutely nothing, they're trying to scare you and cannot garnish your wages without taking you to court and obtaining a judgment first.
5. I have a case that's in my office: This means that it popped up on their computer screen in their tiny little half cubicle.
Don't be intimidated by these people they will try to claim or insinuate they can arrest you, sue you, etc. But in most cases they cannot or will not because you owe less than what it would cost to obtain a judgment. Don't give in to these people, there is no such thing as debtors prison and if you simply cannot pay at this time, sometimes it's just best to let their calls go to voicemail and deal with the debt when you can.
Taken from Richard's comment on http://800notes.com/Phone.aspx/1-972-550-5000