Speechmatics realtime sessions die after 3 minutes with no audio or ping

TL;DR

Realtime sessions close after 3 minutes with no audio or ping/pong, signaled by an in-band error and code 1008. Send pings while your agent thinks, and keep custom dictionaries under 20,000 items.

Steps

1. Realtime sessions close after 3 minutes with no audio or ping/pong, signaled by an in-band error and code 1008.
2. Send pings while your agent thinks, and keep custom dictionaries under 20,000 items.

When to use

You are seeing this: Realtime sessions close after 3 minutes with no audio or ping/pong, signaled by an in-band error and code 1008. Use this skill when you run into "Speechmatics realtime sessions die after 3 minutes with no audio or ping".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Source: Official docs (Speechmatics realtime limits): a realtime session ends after 48 hours, after 1 hour with no audio, or after just 3 minutes with no audio and no ping or pong. Closure arrives as an in-band error plus close code 1008, so handle it as a normal event. If your agent pauses to think, send pings to hold the session. Separately, more than 20,000 custom dictionary items triggers a protocol error with code 1003.

Verified resolution: Realtime sessions close after 3 minutes with no audio or ping/pong, signaled by an in-band error and code 1008. Send pings while your agent thinks, and keep custom dictionaries under 20,000 items.

Source URL: https://github.com/speechmatics/docs/blob/HEAD/docs/speech-to-text/realtime/limits.mdx