diff --git a/src/modules/topos/doc/topos_admin.xml b/src/modules/topos/doc/topos_admin.xml
index b81672b0064..681c5bb9a19 100644
--- a/src/modules/topos/doc/topos_admin.xml
+++ b/src/modules/topos/doc/topos_admin.xml
@@ -192,6 +192,10 @@ modparam("topos", "branch_expire", 300)
dialog_expire (int)
Interval in seconds after which the dialog records are deleted.
+ Keep in mind that the module does not update the dialog timestamp
+ after the initial call setup on re-INVITEs or other in-dialog
+ messages. So set a large enough value (according your longest call
+ duration) to prevent problems in re-writing messages.