By: John Shepler

All businesses require telephone lines in some form. While independent professionals might depend solely on smartphones for wireless communication, businesses with physical locations or multiple employees typically have landlines. Let’s examine the available analog and digital choices, along with the benefits of using telephone trunk lines for increased capacity and cost savings.

Plain Old Analog

Analog phone lines are the traditional technology used by phone companies for over a century. These are often referred to as POTS, or Plain Old Telephone Service. POTS lines are known for their reliability, established infrastructure, and excellent voice quality for local and long-distance calls. Standard phones, including desk phones and cordless systems with multiple handsets, are analog and connect directly to analog business lines.

Broadband Phone

An alternative for a single phone line is using a broadband internet connection shared with computers. While often chosen for its affordability, this option can result in reduced voice quality and might not be compatible with certain devices like fax machines and alarm systems.

Adding More Lines

Businesses with multiple phone lines, particularly those with internal contact centers or specializing in call center services, often have greater needs. Smaller operations might still depend on analog phone lines, adding them individually and connecting them to a key telephone system or PBX switching system. Each line has its own phone number.

How Costs Add Up

Adding analog lines as needed is feasible until the number of lines increases significantly. While there are no technical obstacles, costs rise proportionally. Two lines cost double a single line, and six lines cost six times as much, with no cost savings for using multiple lines.

How Trunking Saves

Trunking is a strategy to reduce costs while maintaining voice quality and reliability. It involves combining multiple lines into a single trunk line with equivalent capacity. This method, developed by the telephone industry for efficiently transmitting numerous calls between switching offices, initially used analog technology known as carrier telephony. In recent times, this process has become entirely digital between offices, with analog POTS lines used only for the final connection to the customer’s location.

T1 Telephone Trunks

The first digital trunk line for businesses was the T1 telephone line, the same technology used for point-to-point or dedicated internet access. The T1 line is divided into 24 segments or time slots, each capable of carrying a two-way conversation, essentially acting as an analog POTS line. A channel bank converts between analog phones and the T1 line, and most in-house PBX systems have a built-in interface for this or can add it easily.

Cost Advantage of T1

T1 trunks become cost-effective compared to multiple POTS lines when exceeding 6 to 10 lines. For businesses needing over a dozen lines, T1 is the less expensive choice. Multiple T1 lines can be added to provide more lines in blocks of 24.

ISDN PRI Improves on T1

ISDN PRI, or Primary Rate Interface, is a newer version of the T1 line. It utilizes the same line but designates one channel for signaling and switching, leaving 23 channels for individual phone lines. Popular for call centers, ISDN PRI enables faster call setup and teardown than T1 lines. It also offers digital data, such as Caller ID, not typically available with standard T1 trunks. Similar to T1, multiple ISDN PRI trunks can be installed as needed. Cost-wise, it’s comparable to T1, and most PBX systems include the PRI interface.

SIP Trunking, The Emerging Standard

While ISDN PRI is currently the standard for commercial telephone trunking, a newer technology, SIP trunking, better supports enterprise VoIP systems. SIP is the switching protocol used by IP telephones and VoIP systems.

SIP vs T1

SIP trunks are also digital but differ from T1 lines by using packet switching instead of time division channelization. Packet switching is fundamental to Ethernet networks used in computing. Companies are transitioning from analog phones to IP phones that utilize the same network as their computers. SIP trunks extend this connection to the service provider, supporting multiple lines or combined voice and data.

Private Lines vs The Internet

High-performance SIP trunks are private lines between the user and the carrier, avoiding the instability of internet broadband phone service. While often capable of providing internet service, SIP trunks prioritize telephone packets for optimal voice quality. SIP trunking is gaining popularity in call centers as businesses replace older PBX systems with newer IP PBX systems or outsource switching to the cloud.

How to Choose

Determining the best telephone trunking solution for your organization requires careful consideration. Consult with experts to understand the tradeoffs and compare pricing from different carriers in your area. Call toll free (888) 848-8749 or submit an inquiry at Telexplainer.net