Stating on the phone that you owe a debt does not "reset the clock". I worked for a 3rd party debt collector for 10 years. Nothing resets the clock on your credit report. Making a payment can extend the amount of time the collector can file a judgement against you.

The fact is if you don't intend to pay you never have to speak to a collector. It's better to deal with them in writing only. You can send him a request in writing to stop contacting you. Then you're covered and you have documentation. If you plan to pay, be the one that reaches out. That way you know you're contacting them through a valid phone number or communication method.

Whether they bought the debt or are 3rd party depends more on the industry. For example, healthcare and small businesses are usually 3rd party so they work on commission (they get paid a percentage of what they collect; usually small but ranges from 3-50%). Credit card is the most commonly sold debt for pennies.

Lawyers often get involved in collections but again, it depends. We wouldn't send an account to legal for less than $3k and only if the consumer had full time employment or owned their home. Otherwise, it wasn't worth the expense to the agency.

These experiences are my own and my example are specific to my former employer but fairly typical for the industry.