Patton electronic SmartNode 4110 Series ユーザーズマニュアル

SIP interface configuration task list

SmartWare Software Configuration Guide 

Additional call transfer support, a push-back mechanism, is enabled by default for SIP interfaces by sending 
REFER messages. 

SmartWare detects calls that are looped internally, i.e. calls that leave the device over the same SIP interface 
over which they enter the device. If an internal loop is detected for a SIP interface, SmartWare sends a REFER 
message to push back the call to the connected network as soon as the call is connected.

ISDN interfaces react similarly to internally looped calls. The push-back mechanism is enabled by default for 
ISDN interfaces (BRI ports) by accepting or rejecting explicit call-transfer (ECT) invocations. An ISDN 
phone that is connected to a BRI port and that has two active calls can send an ECT invocation to connect the 
two calls inside the device. An ISDN interface can be configured to accept or reject ECT invocations.

SmartWare detects calls that are looped internally, i.e. calls that leave the device over the same ISDN interface 
over which they enter the device. If an internal loop is detected for an ISDN interface bound by an ISDN user 
port, SmartWare sends an explicit call-transfer (ECT) to push back the call to the connected network as soon 
as the call is connected. An ISDN interface can be configured to emit ECT invocations.

on page 452 shows an example scenario where a SIP network connects two devices to give a home 

office access to a PBX in the central office.