How to Use GPT 5.6 Sol Fast Mode via the TeamoRouter API | TeamoRouter

Quick Answer

GPT 5.6 Sol Fast mode is a pay-as-you-go speed tier that makes OpenAI's flagship coding model respond up to 2.5x faster than Standard, at 2x the token price, with no change in intelligence. You enable it by sending service_tier: "fast" in your request — no provisioning, no reservations. Through the TeamoRouter API, you add that single field to your existing OpenAI-compatible call and get Fast mode on gpt-5.6-sol immediately, billed at 2x list with your account discount preserved. This guide covers the API details, pricing, when Fast mode is worth it, and complete code examples in Python and JavaScript.

What Is GPT 5.6 Sol Fast Mode?

On July 30, 2026, OpenAI rolled out Fast mode for GPT-5.6 Sol as part of a broader price-performance update. The same announcement also:

• Cut GPT-5.6 Luna prices by 80% (to $0.20/$1.20 per million tokens)
• Cut GPT-5.6 Terra prices by 20% (to $2/$12)
• Left Sol's Standard pricing unchanged at $5/$30
• Renamed the old "Priority Processing" tier to Fast mode, keeping full backward compatibility (requests tagged priority now route to Fast mode)

Fast mode is the API service tier that gives you predictably low latency: tokens are generated faster and at a more consistent speed than Standard, even during peak demand. The intelligence is identical — you are paying purely for speed and scheduling priority.

The Key Numbers

The SLA for Fast mode: 99.9% uptime, with 99% of requests sustaining over 80 tokens per second.

Why Route Fast Mode Through TeamoRouter?

You can call Fast mode directly on OpenAI's API, but routing through TeamoRouter gives you four things that matter in practice:

1. Billing convenience. Pay with Alipay, WeChat Pay, or card instead of maintaining an OpenAI billing account with an overseas card.
2. Direct connectivity. If you are in a region where api.openai.com is unreliable, TeamoRouter's https://api.teamorouter.com/v1 endpoint is reachable directly.
3. One key for everything. The same API key that enables Fast mode on gpt-5.6-sol also works for Claude, Gemini, DeepSeek, and the rest of the model catalog.
4. Transparent billing. Fast requests are marked in your transaction history, and your existing account discount applies to the 2x list price.

Enabling Fast Mode: The Single Field

Fast mode is enabled per request with one field in your payload. It works in both the Chat Completions and the Responses API.

Responses API (Python)

from openai import OpenAI

client = OpenAI(
    api_key="sk-teamo-xxxxxx",
    base_url="https://api.teamorouter.com/v1",
)

resp = client.responses.create(
    model="gpt-5.6-sol",
    input="Refactor this function to remove the nested loops.",
    service_tier="fast",  # <-- Fast mode
)

print(resp.output_text)

Responses API (JavaScript)

import OpenAI from "openai";

const client = new OpenAI({
  apiKey: "sk-teamo-xxxxxx",
  baseURL: "https://api.teamorouter.com/v1",
});

const resp = await client.responses.create({
  model: "gpt-5.6-sol",
  input: "Explain the time complexity of this algorithm.",
  service_tier: "fast", // <-- Fast mode
});

console.log(resp.output_text);

Chat Completions API (Python)

from openai import OpenAI

client = OpenAI(
    api_key="sk-teamo-xxxxxx",
    base_url="https://api.teamorouter.com/v1",
)

resp = client.chat.completions.create(
    model="gpt-5.6-sol",
    service_tier="fast",  # <-- Fast mode
    messages=[
        {"role": "user", "content": "Write a Python script to parse this CSV and summarize it."}
    ],
)

print(resp.choices[0].message.content)

That's the entire integration. If you already call gpt-5.6-sol through TeamoRouter, adding service_tier="fast" is a one-line change.

Legacy Value Still Works

If you have code written for the old Priority Processing tier, it keeps working unchanged:

resp = client.responses.create(
    model="gpt-5.6-sol",
    input="Draft an API design for a rate limiter.",
    service_tier="priority",  # Legacy value — behaves identically to "fast"
)

fast is the current recommended value; priority is still accepted and routes to the same tier. For GPT-5.6 and earlier models, the service_tier field in the response object may still echo "priority" — this is expected and harmless.

Project-Wide Defaults

Per-request is fine for occasional use, but if you want Fast mode as the default for an entire project, set it once. With TeamoRouter you can wrap your client so every call inherits the tier:

from openai import OpenAI

class FastModeClient(OpenAI):
    def __init__(self, *args, **kwargs):
        kwargs.setdefault("base_url", "https://api.teamorouter.com/v1")
        kwargs.setdefault("api_key", "sk-teamo-xxxxxx")
        super().__init__(*args, **kwargs)

client = FastModeClient()

def fast_responses(model, input_text, **kwargs):
    return client.responses.create(
        model=model,
        input=input_text,
        service_tier="fast",  # default for every call
        **kwargs,
    )

Or, if you prefer environment variables, configure your CLI tool once:

export OPENAI_BASE_URL="https://api.teamorouter.com/v1"
export OPENAI_API_KEY="sk-teamo-xxxxxx"

Many OpenAI-compatible clients (Codex, Cline, opencode) let you set a default service_tier in their config. In Codex, for example, add this to ~/.codex/config.toml:

model = "gpt-5.6"
service_tier = "fast"

Streaming with Fast Mode

Fast mode and streaming are a natural pair — the whole point is lower latency. Here is a streaming example using the Responses API:

from openai import OpenAI

client = OpenAI(
    api_key="sk-teamo-xxxxxx",
    base_url="https://api.teamorouter.com/v1",
)

with client.responses.stream(
    model="gpt-5.6-sol",
    input="Write a function that validates an email address and explain it.",
    service_tier="fast",
) as stream:
    for text in stream.text_stream:
        print(text, end="", flush=True)

You'll notice the first token arrives sooner than Standard — that's the latency improvement that matters most for interactive use.

Pricing and Billing: What to Expect

Fast mode is billed at 2x the list price of Standard. Through TeamoRouter, the calculation is:

• gpt-5.6-sol Fast list price: $10 input / $60 output / $1 cached input per million tokens
• Your account discount (if any) applies to that 2x list price
• Fast requests appear with a "Fast" hint in your TeamoRouter billing history

Concretely: if your account has a 10% discount, Fast output costs $60 × 0.9 = $54 per million tokens (not $30 × 0.9 × 2). The discount always applies to the list price of the tier you actually used.

When Fast Mode Is Worth the 2x

A good default: keep Standard as your project baseline, and switch individual latency-sensitive calls to Fast. Because it's per-request, you can A/B test the speedup against your actual workload before committing the spend.

Measuring the Speedup

To verify you're getting the advertised latency, time time-to-first-token (TTFT) and tokens-per-second on the same prompt in both tiers:

import time
from openai import OpenAI

client = OpenAI(api_key="sk-teamo-xxxxxx", base_url="https://api.teamorouter.com/v1")

def time_tier(service_tier, prompt="Write a 500-word technical summary of gRPC."):
    start = time.perf_counter()
    resp = client.responses.create(
        model="gpt-5.6-sol",
        input=prompt,
        service_tier=service_tier,
    )
    elapsed = time.perf_counter() - start
    tokens = len(resp.output_text.split())
    print(f"{service_tier or 'standard'}: {elapsed:.2f}s total, ~{tokens / elapsed:.1f} tok/s")
    return elapsed

time_tier(None)          # Standard
time_tier("fast")        # Fast mode

Run this on your own workload — you'll typically see TTFT drop substantially while throughput (tokens/s) climbs toward the 2.5x ceiling on short prompts. On long generations the improvement is less dramatic, which is why long-context is excluded.

FAQ

What exactly does service_tier "fast" do?

It tells the API to process your request on the Fast tier: higher scheduling priority and faster, more consistent token generation. The model and its intelligence are identical to Standard; only speed and price change.

Is Fast mode the same as Priority Processing?

Yes — it's the same tier, renamed. OpenAI renamed Priority Processing to Fast mode on July 30, 2026. The legacy value priority still works and behaves identically to fast.

How much faster is GPT 5.6 Sol in Fast mode?

Up to 2.5x faster than Standard, per OpenAI's documentation. Real-world speedup varies by prompt length and load; short interactive prompts see the biggest time-to-first-token improvement.

Does Fast mode work with Chat Completions?

Yes. Fast mode works in both the Chat Completions and Responses APIs. Add service_tier: "fast" to either.

Why does TeamoRouter bill Fast at 2x list with my discount on top?

Because that's how the tier is priced upstream: 2x the Standard list price. TeamoRouter preserves your account discount by applying it to the tier's list price, then marks the request with a "Fast" hint in billing so you can audit exactly what you paid.

Can I use Fast mode with models other than GPT-5.6 Sol?

The Fast tier applies to GPT-series models that support it. In the current lineup, gpt-5.6-sol is the flagship that supports Fast mode. For models that don't expose the tier, the field is ignored or omitted — check the model catalog in your TeamoRouter dashboard.

Is Fast mode good for long-context requests?

No — Fast mode excludes long-context requests. If your workload uses very large contexts, use Standard, where full context support is guaranteed.

Summary

GPT 5.6 Sol Fast mode is one field away: service_tier: "fast". Route it through TeamoRouter and you get the same 2.5x speedup with Alipay/WeChat billing, direct connectivity, one key across the whole model catalog, and a "Fast" billing hint on every request. Enable it per request for interactive work, keep Standard for batches, and let the cost follow the latency you actually need.

Get Started

1. Sign up at TeamoRouter
2. Generate your API key
3. Add service_tier="fast" to your next gpt-5.6-sol call at https://api.teamorouter.com/v1

Get Your TeamoRouter API Key →

Full model catalog, floating-rate discounts, and Fast mode — one key at https://api.teamorouter.com/v1.