Prestel
In 1983, the Prestel messaging service known as “Prestel Mailbox” was launched, initially hosted on the computer known as "Enterprise", and later available from all IRC computers by means of a centralised messaging computer known as "Pandora". This facility extended the original day one concept of “Response Frames” whereby an end user could send a message back to the IP who owned the page via special pages, for example to order goods or services. The user’s name, address, telephone number, and date could be added automatically to the message when the IP set up the response frame by means of codes which triggered extraction of key data from the users account held on the IRC computer. Initially response frames were ingathered by an IP from each IRC individually, but later the facility to collect messages from all IRCs at the UDC from where they could be ingathered centrally was implemented, and with the introduction of Mailbox, they could be retrieved from any IRC.
Internet backbone
The first packet-switched computer network was the NPL network, followed closely by the ARPANET. The latter used a backbone of routers called Interface Message Processors. Both the NPL and ARPANET networks were interconnected in 1973, while other packet-switched computer networks began to proliferate in the 1970s, eventually adopting TCP/IP protocols or being replaced by newer networks. The National Science Foundation created NSFNET in 1986 by funding six networking sites using interconnecting links and peering to the ARPANET. In 1987, this new network was upgraded to T1 links for thirteen sites. These sites included regional networks that in turn connected over 170 other networks. IBM, MCI and Merit upgraded the backbone to bandwidth (T3) in 1991. The combination of the ARPANET and NSFNET became known as the Internet. Within a few years, the dominance of the NSFNet backbone led to the decommissioning of the redundant ARPANET infrastructure in 1990.