Billing Company Software

Hello - I have a few questions about how third-party billing companies operate.

1. Do most third-party billing companies use a billing software or do they use their client's EHR to submit claims?
2. If they use a software, is billing software usually compatible with most EHRs?
3. I assume all billing software is ran through a clearinghouse, but what about EHRs?

I'm new to all this and trying to figure out how a third-party billing company would operate. Thank you.

* This article was originally published here