OpenAI Model Changes - Cost & Usage Guide

Introduction

This guide explains the range of OpenAI models available, their associated costs and how each should be used for PBX calls, transcription, analytics, and AI agents. The main aims of this guide can be summarised as follows:

  • Reduce operating costs
  • Standardise defaults
  • Make model selection predictable and explainable

For users who want to compare OpenAI models and pricing in more detail, OpenAI provides an official reference page: https://platform.openai.com/docs/models/ 

Cost vs Accuracy Ratio

Smaller models are more affordable, but less accurate.

  • nano < mini < base < versioned < pro

This rule holds across all OpenAI model families.

Model Cost Tiers (Highest to Lowest)

Focus on Affordability

These models are safe for high‑volume PBX workloads such as call summaries, sentiment analysis, and CRM notes.

Model

Cost Level

Intended Use

gpt-5.4-nano

Lowest

Extremely high volume, simple tasks

gpt-5.4-mini

Low

Default model – best price/performance

gpt-5.4-mini is set as the default as it offers the best quality-to-cost ratio.

Focus on Accuracy

These models should only be used when higher accuracy or reasoning is explicitly required.

Model

Cost Level

Notes

gpt-5.4

High

Advanced summaries, QA audits

Deprecating Models

OpenAI deprecates models as they invest in newer, more efficient architectures.

Reference: https://developers.openai.com/api/docs/deprecations 

Why are they Being Deprecated?

  • Older architecture
  • Worse cost/performance than current mini
  • Less affordable for the same output quality

Transcription Models (PBX Transcription)

Due to these changes, we now expose model selection under: System → Integrations → Transcription → OpenAI.

This allows Administrators to choose the transcription model that best fits their cost and quality requirements.

Call Recording EndPoint APIs Used

  • v1/audio/transcriptions
  • v1/audio/translations

Models

Model

Cost Level

Intended Use

Whisper

Most Affordable

Default for bulk call recording

gpt-4o-mini-transcribe

Medium

Better formatting

gpt-4o-transcribe

Higher

Highest transcription quality

Whisper remains the most cost‑effective option for PBX transcription.

Text & Analysis Models (PBX Analytics)

Summary/Sentiment EndPoint APIs Used

  • v1/chat/completions

Models

  • gpt-5.4 (Default)
  • gpt-5.4-mini
  • gpt-5.4-nano

Realtime Models (Live Calls & AI Agents)

You can use the “Pricing” links to evaluate the cost differences between the offered models.

Calls Endpoint

  • v1/realtime

Models

gpt-realtime-1.5

Text Endpoint

  • v1/responses

Models

  • gpt-5.4-mini (Default)
  • gpt-5.4 (High Accuracy)

Last Updated

This document was last updated 26 May 2026

https://www.3cx.com/docs/open-ai-models/