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Call admission stays on the datasheet

An SBC can refuse a new INVITE when its configured budget is exhausted. The number itself is platform-specific.

Learn in 5 minutes

  1. Describe admission as a local policy
  2. Read 503 as one documented failure response
  3. Refuse invented capacity formulas

Visual

INVITE refused at the budget · study drawing · cyphermonkeylabs.com AliceSBC INVITE 100 503 ACK

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The SIP code is standard. The session budget is not.

Worked example

Read the refusal Step the ladder. Which response refuses the call?

  1. Play until the final response.
  2. Read the status code.
  3. Note that no session count is inside SIP.

Fault

Operators keep raising an undocumented calls-per-second number. New INVITEs still receive 503.

The message is a local refusal. It does not contain a formula.

Quiz

Call admission is


This lesson’s refusal uses


The concurrent-session maximum is found in


A calls-per-second formula printed only in a blog should be


100 Trying before a 503 means


ACK after this 503 is


Ecosystem

Glossary, sister systems, and the integration seam for this room.

AI omni-channel agents A voice bot still needs a session. SIP creates, modifies, and ends sessions. Omni-channel, in the contact-center sense, means the same contact can also live on chat or another digital channel. Those channels do not replace the voice session. On Amazon Connect the platform owns the managed PSTN voice channel. Bridging an outside carrier into Connect with a Chime Voice Connector is not a supported pattern unless AWS reviews it. When an SBC forks the voice leg to a recorder, that fork is SIPREC, a different plane from the customer dialog.

AI agents A voice bot still needs a session. On Amazon Connect the platform owns the managed PSTN voice channel. Bridging an outside carrier into Connect with a Chime Voice Connector is not a supported pattern unless AWS reviews it. The FreeSWITCH manual page also describes SignalWire, founded by the FreeSWITCH team, as a hosted platform with AI agents behind REST APIs and SWML.

Glossary · Ecosystem map · Ports · Troubleshooting

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