What does the provider do when the user connects?

Question

Computer networks

I understand correctly that when switching from one provider to another, on my part it is only necessary:
​​1) Conclude an agreement
2) Enter data: IP, mask, etc.

Answer 1

2) Enter data: IP, mask, etc.

This is not even necessary if there is DHCP.

1) Conclude an agreement

And break the old one.

Answer 2

1) Conclude an agreement

This is, in general, all that is needed. For a long time, physicists have not been given individual settings (because the level for the most part is such that ...), but everything arrives from DHCP. Yurikam - yes, they often give out settings for manual entry.