Nearly every business has a LAN or Local Area Network. Most also have a WAN or Wide Area Network connection. That's what lets you connect to the outside world. Your WAN connection is often an on-ramp to a larger public or private network.
A perfect example is what's called T1 dedicated Internet. Dedicated means that this T1 line is a direct connection from your business to your Internet service provider that is not shared with other users and not used for other purposes. The bandwidth of this line is 1.5 Mbps in both directions, upload and download, at all times. It gives you a responsive, reliable and predictable Internet connection.
In this case, the T1 line is acting as an on ramp to the huge public network that is the Internet. Many business find this arrangement perfectly meets their needs for Web browsing, email, and server connections. If they need more bandwidth, additional T1 lines can be bonded together to create a faster on-ramp.
T1 lines are also ideal on-ramps to private networks such as MPLS networks. An MPLS or Multi-Protocol Label Switching network is a privately run regional or national packet switched network that ties together businesses with multiple locations. Each location has a T1 line for an on ramp that's also an off-ramp, of course. The MPLS network makes sure that every location can connect to every other location with a high quality of service and a high degree of security. MPLS networks are often the most cost effective solution for multi-location businesses.
Another on ramp is the one to the public switched telephone network. T1 PRI lines are used to provide up to 23 separate outside telephone lines to a business PBX telephone system. A T1 line configured as a SIP Trunk does the same thing for enterprise VoIP phone systems. SIP trunks can also be used as on-ramps to both the public telephone network and the Internet with a single line.
What condition is your on ramp in? Does it act like one of those beat up freeway ramps that is in serious need of rebuilding? If so, you should consider new or replacement T1 line service for the qualify and reliability of service your business needs. Prices have never been better than they are right now.