Internet Service can be broken down into:
The interconnections through an ‘Internet Service Provider’ (ISP), provides the media connection (internet signals) across cities and towns in different area’s.
The ISP’s connects their services directly from an ‘Exchange Hub’, traditionally Exchange Hubs connects to a backbone infrastructure which carries copper wire in the ground was originally for Telecommunications Services connecting callers
Eventually the technology spread across countries and continents through copper wire combined with wireless support (Satellite Services).
With the infrastructure leased out to suppliers such as Virgin Media, supplies then supply customers with internet access via a gateway and a DNS service (Domain Name Server).
Depending on the type of line your ISP leases, then you can expect services covering technologies (from DSL, ADSL to SDSL etc..).
With a ADSL a subscriber can run Internet Service and Phone Services simultaneously by installing into the subscriber line (live phone jack) a micro-filter to separate voice (<4KHz) and data (>4KHz) signals for transaction without crosstalk.
Image Credits techyyouth.com