@@ -634,6 +634,10 @@ modparam("acc", "acc_prepare_always", 1)

 			set to 0, the value is saved as empty string (the existing behavior).

 		</para>

 		<para>

+		Database columns may need to be altered to DROP NOT NULL constraints

+		and DROP DEFAULT values in order to accept NULL values.

+		</para>

+		<para>

 		Default value is 0.

 		</para>

 		<example>

@@ -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.

 		</para>

 		<para>

+		Database columns may need to be altered to DROP NOT NULL constraints

+		and DROP DEFAULT values in order to accept NULL values.

+		</para>

+		<para>

 		Default value is 0.

 		</para>

 		<example>