CHAPTER26 Manipulation
Mediant 1000 Gateway & E-SBC | User's Manual
Mapping PSTN Release Cause to SIP Response for Analog
Interfaces
The device's FXO interface interoperates between the SIP network and the PSTN/PBX. This
interoperability includes the mapping of PSTN/PBX Call Progress tones to SIP 4xx or 5xx
responses for IP-to-Tel calls. The converse is also true - for Tel-to-IP calls, the SIP 4xx or 5xx
responses are mapped to tones played to the PSTN/PBX.
When establishing an IP-to-Tel call, the following rules are applied:
■ If the remote party (PSTN/PBX) is busy and the FXO device detects a busy tone, it sends a
SIP 486 Busy response to IP. If it detects a reorder tone, it sends a SIP 404 Not Found (no
route to destination) to IP. In both cases the call is released. Note that if the 'Disconnect Call
on Busy Tone Detection' parameter is set to Disable, the FXO device ignores the detection of
busy and reorder tones and does not release the call.
■ For all other FXS/FXO release types such as:
● no free channels in the Trunk Group,
● an appropriate call routing rule to a Trunk Group doesn’t exist, or
● the phone number isn’t found
the device sends a SIP response to the IP according to the 'Default Release Cause' parameter.
The parameter defines Q.931 release causes. Its default value is 3, which is mapped to the SIP
404 response. By changing its value to 34, the SIP 503 response is sent. Other causes can be
used as well.
Numbering Plans and Type of Number
The IP-to-Tel destination or source number manipulation tables allow you to classify numbers by
their Numbering Plan Indication (NPI) and Type of Number (TON). The device supports all
NPI/TON classifications used in the ETSI ISDN variant, as shown in the table below:
Table 26-13:NPI/TON Values for ETSI ISDN Variant
NPI TON Description
Unknown
[0]
Unknown [0] A valid classification, but one that has no
information about the numbering plan.
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