Hello Nithya,
For early media use you can refer RFC 3960 sec 3.2 (Ringing Tone Generation). For your quick reference , i am pasting few lines below:
In the PSTN, telephone switches typically play ringing tones for the
caller, indicating that the callee is being alerted. When, where,
and how these ringing tones are generated has been standardized
(i.e., the local exchange of the callee generates a standardized
ringing tone while the callee is being alerted). It makes sense for
a standardized approach to provide this type of feedback for the user
in a homogeneous environment such as the PSTN, where all the
terminals have a similar user interface.
With this in mind, a UAC should develop its local policy regarding
local ringing generation. For example, a POTS ("Plain Old Telephone
Service")-like SIP User Agent (UA) could implement the following
local policy:
1. Unless a 180 (Ringing) response is received, never generate
local ringing.
2. If a 180 (Ringing) has been received but there are no incoming
media packets, generate local ringing.
3. If a 180 (Ringing) has been received and there are incoming
media packets, play them and do not generate local ringing.
Note that a 180 (Ringing) response means that the callee is
being alerted, and a UAS should send such a response if the
callee is being alerted, regardless of the status of the early
media session.
To access this RFC you can use below given link:
caller, indicating that the callee is being alerted. When, where,
and how these ringing tones are generated has been standardized
(i.e., the local exchange of the callee generates a standardized
ringing tone while the callee is being alerted). It makes sense for
a standardized approach to provide this type of feedback for the user
in a homogeneous environment such as the PSTN, where all the
terminals have a similar user interface.
With this in mind, a UAC should develop its local policy regarding
local ringing generation. For example, a POTS ("Plain Old Telephone
Service")-like SIP User Agent (UA) could implement the following
local policy:
1. Unless a 180 (Ringing) response is received, never generate
local ringing.
2. If a 180 (Ringing) has been received but there are no incoming
media packets, generate local ringing.
3. If a 180 (Ringing) has been received and there are incoming
media packets, play them and do not generate local ringing.
Note that a 180 (Ringing) response means that the callee is
being alerted, and a UAS should send such a response if the
callee is being alerted, regardless of the status of the early
media session.
To access this RFC you can use below given link:
Regards
Rakesh Hooda
"None of us is as smart as all of us"
Rakesh Hooda
"None of us is as smart as all of us"
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