I am studying about internet structure, ISPs and their interconnection. However, I have trouble connecting some terms and understanding the greater infrastructure of internet in more detail. I will explain my view below so let me know if I am wrong.
First things first, POPs are places where customers are connected to their provider ISP, to have access to the internet (or at least (technically speaking) the provider ISP's network).
COs are places where the coaxial cables from houses are terminated. In COs there is the DSLAM that splits the signals to telephone and internet traffic. COs pretty much handle the last mile connection.
So, let's assume that A is customer of ISP_A and B is customer of ISP_B and ISP_A and ISP_B are connected via transit ISP_C. If A wants to send a datagram to B (skipping the LAN functionality):
The datagram will be passed from A's router to the modem. The modem will transform it into a signal and transmit it to the telephone line.
Finally, the signal will arrive to the local CO, where the DSLAM will infer that the signal is internet traffic.
So it will transmit the datagram to the POP of the corresponding ISP (probably the same telco).
Then the datagram will be routed to the POP of the transit ISP
It will follow the reverse route to arrive to customer B.
Have I got that right?