By: John Shepler

Integrated Services Digital Network Basic Rate Interface (ISDN BRI) has long been considered a top-tier choice for audio connections in studios, film production, and radio broadcasting. However, ISDN BRI service has become increasingly pricey and difficult to obtain. Some traditional telephone companies have even stopped offering new ISDN BRI lines altogether. But don’t worry, this doesn’t mean you’re out of options for remote broadcasts or voice-over work.

New BRI Service, Not From Telcos

The latest development is the introduction of a nationwide ISDN BRI line service from a company specializing in audio production, not telecommunications. To be honest, ISDN BRI isn’t a major revenue generator for telcos. Its applications are niche. Phone companies would prefer to phase it out and focus on services with wider appeal. In some regions, they’re already declining orders for new lines, relocations, or modifications.

Alternative Approaches

So, what options are left for those who rely on high-quality audio connections for their work? One method is recording the audio and transferring it digitally like any other file. While this preserves quality, it lacks real-time capability. Another option is transitioning to internet-based solutions, such as dedicated lines or public internet. Dedicated lines offer the necessary quality and speed, but their reach is limited to specific points. The internet, while widely accessible, often falls short in terms of real-time audio performance.

ISDN BRI Still Holds the Crown

The optimal choice remains ISDN BRI, but sourced from a nationwide provider, not your local phone company. Source Elements, a prominent name in professional audio, now offers ISDN BRI service alongside their IP audio and other offerings.

ISDN BRI’s strength lies in its established and widely accepted method of delivering high-quality live audio between equipped locations. It’s a dial-up service akin to your regular phone line. Dial the ISDN number of the desired location, establish a connection between the terminal equipment at both ends, and enjoy an FM broadcast-quality link for the call’s duration.

BRI For Voice Acting

ISDN BRI is particularly popular in the voice acting and voice-over industry. This technology enables professional voice artists to work remotely without being physically present in the studio. This includes tasks like ADR (Automated Dialogue Replacement) or “looping” for film. The setup requires an ISDN BRI connection and a CODEC (Coder/Decoder) at each end to manage analog-to-digital-to-analog conversions. Standard microphones and mixing boards can then feed audio to the CODEC.

How It Works

Think of ISDN BRI as a superior phone line, which it essentially is. ISDN stands for Integrated Services Digital Network. It leverages the existing infrastructure and wiring of the public telephone system. Each ISDN line has its own phone number and can call any other ISDN line.

The key difference lies in the signal itself. ISDN transmits digital signals instead of analog currents. Two main versions exist: BRI and PRI. BRI, or Basic Rate Interface, comprises two “B” (bearer) channels and one “D” (delta) channel. The bearer channels transmit the digital audio, while the D channel handles system signaling. The bearer channels can operate independently at 64 Kbps each or be combined for a 128 Kbps channel. Combining two channels and applying compression techniques like AAC or MP3 delivers studio-grade microphone quality.

Bidirectional and Low Latency

Crucially, ISDN circuits are bidirectional, a significant advantage for audio applications. This allows a voice actor, for example, to speak into a microphone and simultaneously receive instructions through headphones without the annoying latency or delay often experienced with internet-based solutions. ISDN isn’t affected by network congestion, so signal dropouts are not an issue.

BRI vs PRI

You might be familiar with ISDN’s more robust offering, PRI (Primary Rate Interface), commonly used for telephone trunking in PBX business phone systems. While structured similarly to BRI, it boasts 23 B channels and one D channel, allowing for 23 concurrent calls. PRI is expected to remain relevant for the foreseeable future, although it faces competition from SIP Trunks in the telephony transport arena.

How to Get New ISDN BRI Service

If you have an audio-related need, such as a voice-over or voice acting business, a radio station requiring high-quality remote broadcasts or studio-transmitter links, or a production studio needing to connect with talent and other studios, ISDN BRI might still be your ideal solution. Request a quote for competitively priced ISDN BRI service tailored to your location today.