Zero Hop Wideband Voice

Preserving HD audio across international voice paths terminating on U.S. mobile networks

The Problem

International calls terminating in the United States typically pass through multiple intermediate carrier networks before reaching the destination mobile operator. Each additional carrier domain is an opportunity for transcoding, and transcoding usually means the call arrives as narrowband audio regardless of what the originating network sent.

The result is simple. Both endpoints support HD voice, but the subscriber hears audio that reflects the limitations of a multi-carrier transit chain rather than the capabilities of the originating and terminating networks.

This creates a gap between what networks are capable of delivering and what subscribers and downstream systems actually receive.

That gap is becoming more visible as voice quality directly impacts both customer experience and how machines interpret conversations.

The Approach

Zero Hop Wideband Voice describes a direct IP interconnect model that delivers AMR-WB audio from the originating carrier directly into U.S. mobile network interconnect platforms, including AT&T, Verizon, and T-Mobile, without intermediate carrier domains altering or degrading the media.

The objective is straightforward:

Maintain codec integrity from the originating carrier to the destination mobile network by eliminating unnecessary carrier domains.

Architecture

The model is based on three principles:

Direct SIP/IP interconnect
Traffic moves through a direct peering relationship rather than a wholesale routing chain. This avoids signaling translation and media re-anchoring introduced by intermediate carriers.

Codec preservation by default
Where both networks support AMR-WB, calls remain in wideband format end-to-end. If adaptation is required, it occurs at a single controlled interconnect point rather than across multiple carrier domains.

Eliminating intermediate carrier domains
Removing unnecessary carrier domains simplifies the media path, reduces processing delay, and prevents codec decisions made by parties without visibility into the end-to-end quality objective.

Why It Matters Beyond the Human Listener

Voice is increasingly consumed by machines. Speech recognition platforms, conversational systems, analytics engines, and voice-enabled applications all depend on the quality of the audio signal they receive.

Narrowband audio constrains the accuracy ceiling of these systems. Delivering wideband audio consistently improves recognition accuracy, model performance, and the reliability of downstream processing.

What Direct Interconnect Delivers

Compared to traditional multi-carrier international routing:

Lower latency
Fewer carrier domains shorten the media path.

Higher and more consistent audio quality
AMR-WB continuity is preserved end-to-end or maintained at a single controlled interconnect point.

Simpler routing
Direct interconnect reduces dependence on transit carriers and the signaling complexity they introduce.

Reduced cost
Fewer carrier domains remove layers of transit cost.

Greater control and security
Limiting exposure to third-party carrier domains reduces the surface area for media interception, modification, and unpredictable routing behavior.

Extending the Model

The same logic applies in the outbound direction.

Calls originating on U.S. mobile networks are frequently downgraded early in the international routing path due to multi-carrier transit and codec conversion.

Direct interconnect between U.S. mobile networks and international carriers enables AMR-WB preservation in both directions. This creates consistent, end-to-end HD voice paths between participating networks without relying on the broader wholesale ecosystem to maintain codec integrity.

Interconnect Sandbox

Operators evaluating this model are invited to participate in a controlled interconnect sandbox.

Testing typically uses standard SIP interconnect methods and existing test numbers without requiring changes to production routing policies.

Measurements focus on:

• AMR-WB continuity across the full call path
• Detection and location of transcoding events
• SIP signaling transparency
• Direct interconnect versus multi-hop quality comparison

The outcome is a concrete, measured view of how current routing decisions affect codec preservation and what changes when intermediate carrier domains are removed.

Technical Considerations

Zero Hop Wideband Voice is based on a direct interconnect model with the following characteristics:

AMR-WB continuity
Wideband audio remains intact from the originating network to the terminating U.S. mobile operator when both endpoints support it.

Transcoding avoidance
Codec conversion is avoided by eliminating intermediate carrier domains.

SIP signaling transparency
Signaling remains intact to support proper codec negotiation and session establishment between directly interconnected networks.

Direct routing model
Traffic is delivered through direct IP interconnect into U.S. mobile networks without multi-carrier transit, preserving media integrity across the call path.

Call Path Comparison