The integration designation of Integrated T1 service refers to a merging of voice and data, that's telephone and Internet, on a single T1 line. This is done for efficiency and cost minimization, while maintaining telecom quality.
T1 telephone service has long been the gold standard for "trunk lines" that bring in many telephone lines to a business location. T1 is a digital line service that replaces single analog phone lines. The line is segmented into 24 separate channels. Each is the equivalent of a single analog phone line. With a special configuration called T1 PRI, one channel is dedicated to signaling and data, including Caller ID.
T1 DIA or Dedicated Internet Access is the equivalent gold standard for business Internet service. Here the line is configured as a single broadband "pipe" rather than dividing it into channels. The capacity of a T1 line is 1.5 Mbps in both the upload and download directions. That's plenty of bandwidth for nearly all small businesses who need access to the Internet, data exchange with the main office, access to remotely located servers, and POS connections for inventory management and credit card authorizations.
A medium size business may very well order a T1 PRI telephone line with 23 local and/or long distance lines plus a T1 DIA line for Internet service. As the business grows, additional T1 lines can be connected to increase capacity as needed. But what if 23 phone lines are way more than you need? You want the SLA (Service Level Agreement) that guarantees performance of your voice and data lines. But is there any way to cut the cost since you don't really need all that capacity?
That's what Integrated T1 line service gives you. You can designate up to 12 channels for telephone service. Many smaller businesses, including real estate offices and retail stores, need only 6 to 12 anyway. The rest of the bandwidth is assigned to dedicated Internet access. That gives you a minimum of 750 Kbps to 1 Mbps of dependable broadband.
A popular variation of Integrated T1 service is called Dynamic T1. With this service any bandwidth not being used to serve telephone calls in progress is assigned to Internet bandwidth. This make more efficient use of your line so you can get the best voice quality for phone calls and the most bandwidth for Internet access.
If your small business location depends on both reliable high quality telephone service and solid reliable access to the Internet or VPN (Virtual Private Network) connections to your other business locations, the service you'll want to price and consider is Integrated T1.