>>19517370 pb
Nothing is every truly deleted on the Internet (interception).
The splicer collects all data coming through it, your government / militaries put the splicers on all of the major cable lines to collect data coming through it. As for all of the cables under the oceans connecting the continents, they definitely have been spliced too.
Wireless signals can be intercepted in too many ways to list. Programs like Wireshark will help you understand how picking up wireless packets work.
Nothing really complicated about it.