Work on docs

docs/nmt.html

@@ -531,6 +531,7 @@ DMS re-uses the existing signaling hardware of the mobile phone and offers a dat
 Caller ID was added to the system.
 The caller ID is transmitted before the first ringing order.
 It is repeated between ringing orders, in case of lost frames.
+To enable sending caller ID, use '-I 1' option with this software.
 </p>
 
 <p class="toppic">