diff --git a/src/modules/acc/doc/acc_admin.xml b/src/modules/acc/doc/acc_admin.xml
index d1c007312e9..f88d403d2b5 100644
--- a/src/modules/acc/doc/acc_admin.xml
+++ b/src/modules/acc/doc/acc_admin.xml
@@ -634,6 +634,10 @@ modparam("acc", "acc_prepare_always", 1)
set to 0, the value is saved as empty string (the existing behavior).
+ Database columns may need to be altered to DROP NOT NULL constraints
+ and DROP DEFAULT values in order to accept NULL values.
+
+
Default value is 0.
@@ -1157,6 +1161,10 @@ modparam("acc", "cdr_extra", "c1=$dlg_var(caller);c2=$dlg_var(callee)"
If set to 1, custom CDR fields not defined in config operation (or set to $null) will be saved as NULL.
+ Database columns may need to be altered to DROP NOT NULL constraints
+ and DROP DEFAULT values in order to accept NULL values.
+
+
Default value is 0.