User's Manual  134  Document #: LTRT-42060 
  Mediant 2600 E-SBC 
  To enable NAT resolution using the First Incoming Packet mechanism: 
1.  Open the General Settings page (Configuration tab > VoIP menu > Media > General 
Media Settings). 
2.  Set the 'NAT Mode parameter to one of the following: 
•  [0] Auto-Detect  
•  [1] NAT Is Not Used 
•  [2] NAT Is Used  
3.  Click Submit. 
 
12.9.2.2.2 No-Op Packets 
The device's No-Op packet support can be used to verify Real-Time Transport Protocol 
(RTP) and T.38 connectivity, and to keep NAT bindings and Firewall pinholes open. The 
No-Op packets are available for sending in RTP and T.38 formats. 
You can control the activation of No-Op packets by using the ini  file parameter 
NoOpEnable. If No-Op packet transmission is activated, you can control the time interval in 
which No-Op packets are sent in the case of silence (i.e., no RTP or T.38 traffic). This is 
done using the ini file parameter NoOpInterval. For a description of the RTP No-Op ini file 
parameters, see ''Networking Parameters'' on page 548. 
  RTP No-Op: The RTP No-Op support complies with IETF Internet-Draft draft-wing-
avt-rtp-noop-03 ("A No-Op Payload Format for RTP"). This IETF document defines a 
No-Op payload format for RTP. The draft defines the RTP payload type as dynamic. 
You can control the payload type with which the No-Op packets are sent. This is 
performed using the RTPNoOpPayloadType ini parameter (see ''Networking 
Parameters'' on page 
548). The default payload type is 120. 
  T.38 No-Op: T.38 No-Op packets are sent only while a T.38 session is activated. Sent 
packets are a duplication of the previously sent frame (including duplication of the 
sequence number). 
 
Note: Receipt of No-Op packets is always supported.