diff --git a/res/res_pjsip.c b/res/res_pjsip.c
index 1e5d25705b32b218833f0f92835ed6df2bad11f6..e7c83d9d160a96694ba164e095187970c3ff5c34 100644
--- a/res/res_pjsip.c
+++ b/res/res_pjsip.c
@@ -249,6 +249,11 @@
 				</configOption>
 				<configOption name="rewrite_contact">
 					<synopsis>Allow Contact header to be rewritten with the source IP address-port</synopsis>
+					<description><para>
+						On inbound SIP messages from this endpoint, the Contact header will be changed to have the
+						source IP address and port. This option does not affect outbound messages send to this
+						endpoint.
+					</para></description>
 				</configOption>
 				<configOption name="rtp_ipv6" default="no">
 					<synopsis>Allow use of IPv6 for RTP traffic</synopsis>