In order to protect servers from overload and DoS attacks, enterprises may limit the amount of calls to or from a specific peer or device, by the number of new calls within a given period and/or by the overall limit of concurrent calls.
Rate Limiting on SIP methods is to determine the number of INVITEs or new calls (or other SIP methods) that the SBC is going to allow to traverse through to the VoIP servers. This is beneficial when wanting to restrict the number of new calls presented in a given period of time.
Concurrent Session Limiting is used on the SBC to limit the number of overall concurrent calls. This policy limits the overall call capacity dynamically between the peers.
SBCs are designed to dynamically apply limiting policies. If the limit is reached, the peer or device will be blocked for the duration of the limit period.
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