gpt-4o

GPT-4o ("o" for omni) is OpenAI's flagship multimodal model and one of the most widely deployed LLMs in production. On CallMissed you call it with the exact same model id OpenAI publishes — `gpt-4o` — on the standard OpenAI-compatible `/v1/chat/completions` endpoint. That means every SDK, LangChain integration, and curl example written for OpenAI works unchanged: swap the base URL to `https://api.callmissed.com` and keep `"model": "gpt-4o"`.

OpenAI documents GPT-4o as a text-and-image-in, text-out model with a 128,000-token context window and up to 16,384 tokens of output per request (see platform.openai.com/docs/models/gpt-4o). It supports streaming, function calling, structured outputs, and vision — you can pass image URLs or base64 parts in the `messages` array exactly as you would against the OpenAI API. Knowledge cutoff for the current snapshot family is October 2023; for time-sensitive tasks you should ground the model with retrieval or explicit dates in the system prompt.

When OpenAI announced GPT-4o on May 13, 2024, the emphasis was speed and cost relative to GPT-4 Turbo while matching or exceeding it on reasoning, coding, and multilingual tasks (openai.com/index/hello-gpt-4o). The system card reports strong performance across MMLU-style knowledge evaluations, coding benchmarks, and multimodal understanding — useful for teams that need one dependable model for chat, document Q&A, lightweight agents, and image understanding without maintaining separate vision and text stacks.

Pricing on CallMissed follows OpenAI's public list rates at $2.50 per million input tokens and $10.00 per million output tokens, with prompt caching billed at $1.25 per million cached input tokens when supported. That makes GPT-4o a sensible default for production assistants that mix short turns with occasional long context, and for agent loops where tool results inflate prompt size — caching repeated system prompts and tool schemas materially reduces cost.

Typical workloads include customer-support copilots that read screenshots, internal knowledge bots over PDFs and slides, code assistants that accept repository snippets, and multi-step tool-using agents. GPT-4o is not a dedicated "reasoning" model like GPT-5 mini — it accepts temperature and top_p tuning — so it behaves predictably in applications that rely on sampling control. For the hardest math, planning, or multi-hour autonomous jobs, teams often pair GPT-4o for interactive turns with a reasoning-tier model for background planning.

Integration notes: use Bearer auth with your CallMissed API key, set `stream: true` for responsive UIs, and cap `max_tokens` to your latency budget. Vision inputs increase token usage; resize images when possible. GPT-4o does not accept audio or video on the model card — use the speech models (`whisper`, `gpt-4o-transcribe`, or realtime voice) for audio pipelines. Because the model id has no provider prefix, it is distinct from slash-prefixed ids like `openai/gpt-5.4` elsewhere in the catalog — always pass `gpt-4o` exactly for this deployment.

Benchmark and capability context: OpenAI's GPT-4o system card and launch materials emphasized parity with GPT-4 Turbo on graduate-level knowledge (MMLU-style tasks) while cutting latency and cost for multimodal workloads. In practice, teams report GPT-4o as the default for vision Q&A (charts, UI screenshots, receipts) and for multilingual chat where a single model must handle mixed-language user input. On coding, it remains strong for snippet-level fixes and explanation, though OpenAI now positions GPT-4.1 and GPT-5 tiers for repository-scale refactors.

Migration from legacy CallMissed ids: always use `"model": "gpt-4o"`. Any legacy prefixed ids still resolve server-side, but documentation, pricing pages, and new projects should use the maker id only. The HTTP endpoint, headers, and response schema are unchanged.

Operational checklist: (1) Pin system prompts and tool definitions at the top of messages for cache-friendly layouts when caching is enabled. (2) Set `max_tokens` based on UX — 16K is the model maximum but rarely needed in chat. (3) For vision, prefer high-detail images only when OCR matters; downscale large PNGs. (4) Log `usage.prompt_tokens` and `usage.completion_tokens` per request for finance dashboards. (5) Implement exponential backoff on 429 rate limits.

Frequently asked comparisons: vs `gpt-4.1` — choose GPT-4o for general multimodal chat up to 128K; choose GPT-4.1 when you must ingest near-million-token corpora in one shot. vs `gpt-5-mini` — GPT-4o allows classic temperature tuning and is better for interactive vision; GPT-5 mini is for reasoning-heavy text tasks at lower cost. vs the slash-prefixed `openai/gpt-5.4` — different routing path and pricing; do not assume identical latency or snapshot.

Security and compliance: prompts and outputs traverse CallMissed's gateway. Apply your own PII redaction before sending customer transcripts. Do not embed secrets in prompts. For regulated industries, pair model use with audit logging on your side — CallMissed provides usage metering, not content retention guarantees unless your contract specifies otherwise.