Three situations can follow the transfer:
1. A quick confirmation tone (temporarily using the call waiting indication tone) followed by a
dialtone. This indicates the transfer was successful (transferee has received a 200 OK from
transfer target). A can either hang up or make another call.
2. A quick busy tone followed by a restored call (on supported platforms only). This means the
transferee has received a 4xx response for the INVITE and we will try to recover the call. The
busy tone indicates the transfer has failed.
3. Busy tone keeps playing. This means we have failed to receive the second NOTIFY from the
transferee and the call has timed out.
Note: this does not indicate the transfer has been successful, nor does it indicate the transfer has
failed. When transferee is a client that does not support the second NOTIFY (such as our own
earlier firmware), this situation occurs. In bad network scenarios, this could also happen,
although the transfer may have been completed successfully.
Attended Transfer
This function is applicable on the FXS port for VoIP calls only. Assume that parties A and B are in
conversation. Party A wants to Attend Transfer Party B to C:
1. A presses FLASH on the analog phone to get a dial tone;
2. A then dial C’s number followed by #.
3. If C answers the call, A and C are in conversation. Then A can hang up to complete transfer.
4. If C does not answer the call, A can press “flash” back to talk to B.
NOTE: When Attended Transfer fails and A hangs up, the HT503 will ring user A back again to remind
A that party B is still on the call. Party A can pick up the phone to resume a conversation with party B.
3-WAY CONFERENCING
The HT503 supports both Star Code Style and Bellcore Style 3-way conferencing.
Star Code Style 3-way Conference
This function is applicable on the FXS port for VoIP calls only. Assume that parties A and B are in
conversation. Party A wants to bring C into a 3-way conference:
1. A presses FLASH (on the analog phone, or Hook Flash for old model phones) to get a dial tone.
2. A dials *23 then C’s number then # (or wait for 4 seconds).
3. If C answers the call, then A presses FLASH to bring B, C in the conference.
4. If C does not answer the call, A can press FLASH back to talk to B.
5. If A presses FLASH during conference, C will be dropped out.
NOTE: “Enable Call Feature” has to be set to YES in FXS PORT in the web configuration page.
Bellcore Style 3-way Conference
To use the Bellcore Style conference, the “Use Bell-style 3-way Conference” field in FXS PORT web
configuration must be enabled.
Assume that parties A and B are in conversation. Party A (using the HT503) wants to bring C into a 3-
way conference:
Grandstream Networks, Inc. HT503 User Manual Page 12 of 35
Firmware 1.0.0.6 Last Updated: 6/2007