diff --git a/modules/topoh/README b/modules/topoh/README
index 6895a33a266..8812b7b1ab5 100644
--- a/modules/topoh/README
+++ b/modules/topoh/README
@@ -147,6 +147,10 @@ modparam("topoh", "mask_ip", "192.168.0.1")
encode Call-id in such cases. Well-known extensions such as call
transfer or conference join will be added to work with encoded Call-id.
+ NOTE: if you are using dialog module to terminate calls and this
+ parameter is enabled, you must set the dialog module parameter
+ 'lreq_callee_headers' to include the header: 'TH: dlh\r\n'.
+
Default value is 0 (do not mask).
Example 1.3. Set mask_callid parameter
diff --git a/modules/topoh/doc/topoh_admin.xml b/modules/topoh/doc/topoh_admin.xml
index f932b3e2a3a..fd588cd5f32 100644
--- a/modules/topoh/doc/topoh_admin.xml
+++ b/modules/topoh/doc/topoh_admin.xml
@@ -117,6 +117,11 @@ modparam("topoh", "mask_ip", "192.168.0.1")
call transfer or conference join will be added to work with encoded
Call-id.
+
+ NOTE: if you are using dialog module to terminate calls and this
+ parameter is enabled, you must set the dialog module parameter
+ 'lreq_callee_headers' to include the header: 'TH: dlh\r\n'.
+
Default value is 0 (do not mask).