vendor-specific attribute introduced on Maxim's request

etc/sip_dictionary

@@ -48,6 +48,7 @@ ATTRIBUTE	Callback-Id		20	string
 ATTRIBUTE	Framed-Route		22	string
 ATTRIBUTE	Framed-IPX-Network	23	ipaddr
 ATTRIBUTE	State			24	string
+ATTRIBUTE	Vendor-Specific		26	string
 ATTRIBUTE	Session-Timeout		27	integer
 ATTRIBUTE	Idle-Timeout		28	integer
 ATTRIBUTE	Termination-Action	29	integer