Fax Support - Grandstream Networks HT503 User Manual

Configuration page and requires SIP Server configuration and support. The special dial plan feature must
be activated in the SIP Server. An outbound call will be sent directly to the assigned FXO port account,
where there the HT503 will initiate a call to the local CO. The RequestURI header in the INVITE
message contains the phone number used to initiate the call to the local CO.

FAX SUPPORT

HT503 supports FAX in two modes: 1) T.38 (Fax over IP) and 2) fax pass through. T.38 is the preferred
method because it is more reliable and works well in most network conditions. If the service provider
supports T.38, please use this method by selecting Fax mode to be T.38 (default). If the service provider
does not support T.38, pass-through mode may be used. To send or receive faxes in fax pass through
mode, users must select all the Preferred Codecs to be PCMU/PCMA (G.711-µ/a).
HT503 USER MANUAL
FIRMWARE VERSION 1.0.6.8 Page 20 of 48