First
Ring FSK
a) Bellcore/ETSI OnhookPost-Ring FSK
Polarity
Reversal First
Ring
CAS
(DTAS) DTMF/
FSK
Polarity
Reversal CAS
(DTAS) FSK
CAS
(DTAS) Wait For
ACK FSK
OSI FSK
d) Bellcore OnhookFSK w/o Ring
f) Bellcore/ET I OffhookFSKS
c) ETSI OnhookPre-Ring FSK/DTMF
e) ETSI OnhookFSK w/o Ring
DTMF
b) ETSI OnhookPost-Ring DTMF
First
Ring
PHONE ADAPTER Caller ID Delivery Architecture
7.2.24. Streaming Audio Server – SAS
This feature allows one to attach an audio source to one of the PHONE ADAPTER FXS ports and
use it as a streaming audio source device. The corresponding Line (1 or 2) can be configured as a
streaming audio server (SAS) such that when the Line is called, the PHONE ADAPTER answers the
call automatically and starts streaming audio to the calling party provided the FXS port is off-hook. If
the FXS port is on-hook when the incoming call arrives, the PHONE ADAPTER replies with a SIP 503
response code to indicate “Service Not Available.” If an incoming call is auto-answered, but later the
FXS port becomes on-hook, the PHONE ADAPTER does not terminate the call but continues to
stream silence packets to the caller. If an incoming call arrives when the SAS line has reached full
capacity, the PHONE ADAPTER replies with a SIP 486 response code to indicate “Busy Here”.
The SAS line can be setup to refresh each streaming audio session periodically (via SIP re-INVITE)
to detect if the connection to the caller is down. If the caller does not respond to the refresh message,
the SAS line will terminate the call so that the streaming resource can be used for other callers.
7.2.25. Music On Hold – MOH
On a connected call, the PHONE ADAPTER may place the remote party on call (the only way to do
this on te PHONE ADAPTER is to perform a hook-flash to initiate a 3-way call or to swap 2 calls
during call-waiting). If the remote party indicates that they can still receive audio while the call is
holding, the PHONE ADAPTER can be setup to contact an auto-answering SAS as described in
Section 4 and have it stream audio to the holding party. When used this way, the SAS is referred to
as a MOH Server.
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