Step 3: C pickup the phone, dial “*6” + the number of B. C sends the INVITE request to
server, and the callee number is “*6” + the number of B;
Step 4: Server transfer the call of B to C, B stops ringing, and the call between A and C
is established.
6
6
.
.
3
3
F
F
X
X
O
O
M
M
o
o
d
d
e
e
6
6
.
.
3
3
.
.
1
1
I
I
P
P
-
-
T
T
o
o
-
-
P
P
S
S
T
T
N
N
For IP-To-PSTN direction, it can be divided into 2 phases: IP-FXO and FXO-PSTN; and
according to the call establishing way, it can be divided into: One-stage and Two-stage.
Under One-stage mode, secondary dial is not required for the user of IP side; FXO gateway
can get the callee number of PSTN side, and send it to PSTN side automatically.
Under Two-stage mode, secondary dialing is necessary for the caller of IP side.
Tips:
Under dual mode, IP-To-PSTN can not work.
6
6
.
.
3
3
.
.
1
1
.
.
1
1
O
O
n
n
e
e
-
-
s
s
t
t
a
a
g
g
e
e
Fig 67
One-stage flow
One-stage can help user to avoid doing the secondary call, the product can do the call
of FXO-PSTN phase automatically, and the key point is how to get the callee number of
PSTN side. In Figure 67:
