User's Manual 206 Document #: LTRT-27055
Mediant 1000B Gateway & E-SBC
14.4.1 SIT Event Detection
The device can detect and report the following Special Information Tones (SIT) types from
the PSTN:
SIT-NC (No Circuit found)
SIT-IC (Operator Intercept)
SIT-VC (Vacant Circuit - non-registered number)
SIT-RO (Reorder - System Busy)
There are additional three SIT tones that are detected as one of the above SIT tones:
The NC* SIT tone is detected as NC
The RO* SIT tone is detected as RO
The IO* SIT tone is detected as VC
The device can map these SIT tones to a Q.850 cause and then map them to SIP 5xx/4xx
responses, using the parameters SITQ850Cause, SITQ850CauseForNC,
SITQ850CauseForIC, SITQ850CauseForVC, and SITQ850CauseForRO.
Table 14-2: Special Information Tones (SITs) Reported by the device
Special
Information
Tones (SITs)
Name
Description First Tone
Frequency
Duration
Second Tone
Frequency
Duration
Third Tone
Frequency
Duration
(Hz) (ms) (Hz) (ms) (Hz) (ms)
NC1 No circuit found 985.2 380 1428.5 380 1776.7
380
IC Operator intercept 913.8 274 1370.6 274 1776.7
380
VC Vacant circuit (non
registered number)
985.2 380 1370.6 274 1776.7
380
RO1 Reorder (system
busy)
913.8 274 1428.5 380 1776.7
380
NC* - 913.8 380 1370.6 380 1776.7
380
RO* - 985.2 274 1370.6 380 1776.7
380
IO* - 913.8 380 1428.5 274 1776.7
380
The following example shows a SIP INFO message sent by the device to a remote
application server notifying it that SIT detection has been detected:
INFO sip:5001@10.33.2.36 SIP/2.0
Via: SIP/2.0/UDP 10.33.45.65;branch=z9hG4bKac2042168670
Max-Forwards: 70
From: <sip:5000@10.33.45.65;user=phone>;tag=1c1915542705
To: <sip:5001@10.33.2.36;user=phone>;tag=WQJNIDDPCOKAPIDSCOTG
Call-ID: AIFHPETLLMVVFWPDXUHD@10.33.2.36
CSeq: 1 INFO
Contact: <sip:2206@10.33.45.65>
Supported: em,timer,replaces,path,resource-priority
Content-Type: application/x-detect
Content-Length: 28
Type= CPT
SubType= SIT-IC
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