Calls loop prevention

The customer has faced issues with call looping in case of off-net calls or calls between two platforms. Currently there is no feature to detect and prevent this.

Thus it's required to have a feature that can detect and stop loops from escalating, so other calls are uninterrupted/ not disturbed, as the main issue is that call looping takes too much capacity of connections, so this can affect further normal calls processing. Moreover it also uses a lot of resources to authenticate, authorize and route the calls.

Additional Info

The straightforward method of preventing excessive looping is to limit the amount of calls being established at the same moment. We already have simultaneous calls limitation mechanisms in place and it is usually configured as fraud preventive measure, but since it only sees the connected calls it is too late to count in the looping call. For stopping the loop we need to know about the calls in the early establishment stage, so when the looping calls comes back to platform we already have the record about the session.

The normal mode for producing the accounting is:

1. TCONNECT: Start: setup_time=TPROGRESS,connect_time=TCONNECT
2. TDISCONNECT: Stop: setup_time=TPROGRESS,connect_time=TCONNECT,disconnect_time=TDISCONNECT

The idea is to introduce optional progress mode when originate Start accounting for the call is sent to BE ASAP - at TPROGRESS time:

Progress mode accounting:

1. TPROGRESS: Start: setup_time=TPROGRESS
2. TCONNECT: Alive: setup_time=TPROGRESS,connect_time=TCONNECT
3. TDISCONNECT: Stop: setup_time=TPROGRESS,connect_time=TCONNECT,disconnect_time=TDISCONNECT

We have to figure out what is the exact signaling moment to catch up so it is already in place when the call loops in and asks for another authorization. At the same time we do not want to produce unnecessary Start accounting too early - each Start must be followed by corresponding Stop and they consume the resources on BE. The way of determining that mode can again be configurable.

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Definitions, acronyms and abbreviation