Grandstream HT503 User Manual - Manual (Page 24)

FIRMWARE VERSION 1.0.14.1 HT503 USER MANUAL Page 22 of 64
2. A dials 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 the conference, C will be dropped out.
6. If A hangs up, the conference will be terminated for all three parties when configuration
“Transfer on Conference Hangup” is set to “No”. If the configuration is set to “Yes”, A will
transfer B to C so that B and C can continue the conversation.
PSTN PASS THROUGH
HT503 supports PSTN pass through using the FXS port. The user can place and receive PSTN calls
using analog phone connected to FXS port.

To receive PSTN calls, pick up the phone when it rings;

To complete a PSTN call, press the PSTN access code (*00 is default, or any number configured
in the web configuration) to switch to the PSTN line, listen for a dial tone, then dial the number.

If the 503 loses power or lost registration with SIP server, device will switch to mode when PSTN
line will be transparently connected directly to phone connected to FXS port. It will function as a
jack, enabling a direct connection to the PSTN Line.