NAT and STUN Parameters

The Network Address Translation (NAT) and Simple Traversal of UDP through NAT (STUN) parameters are described in the table below.

NAT and STUN Parameters

Parameter

Description
STUN Parameters

[EnableStunForward]

Enables the device to forward incoming STUN packets (RFC 3849).

■ [0] = (Default) Disable. The device doesn't forward received STUN packets.
■ [1] = Enable. The device forwards received STUN packets.

Note: The parameter is applicable only to the SBC application.

NAT Parameters

'NAT Traversal'

configure voip > media settings > disable-NAT-traversal

[NATMode]

Enables the NAT traversal feature for media when the device communicates with UAs located behind NAT.

■ [0] Enable NAT Only if Necessary = NAT traversal is performed only if the UA is located behind NAT:
✔ UA behind NAT: The device sends the media packets to the IP address:port obtained from the source address of the first media packet received from the UA.
✔ UA not behind NAT: The device sends the packets to the IP address:port specified in the SDP 'c=' line (Connection) of the first received SIP message.

Note: If the SIP session is established (ACK) and the device (not the UA) sends the first packet, it sends it to the address obtained from the SIP message and only after the device receives the first packet from the UA does it determine whether the UA is behind NAT.

■ [1] Disable NAT = (Default) The device considers the UA as not located behind NAT and sends media packets to the UA using the IP address:port specified in the SDP 'c=' line (Connection) of the first received SIP message.
■ [2] Force NAT = The device always considers the UA as behind NAT and sends the media packets to the IP address:port obtained from the source address of the first media packet received from the UA. The device only sends packets to the UA after it receives the first packet from the UA (to obtain the IP address).
■ [3] NAT by Signaling = The device identifies whether or not the UA is located behind NAT based on SIP signaling. The device assumes that if signaling is behind NAT that the media is also behind NAT, and vice versa.
✔ UA behind NAT: The device sends media according to option Force NAT (2). If the 'Media Latch Mode' parameter is configured to Strict, the 'Media Latch Mode' parameter automatically changes to Dynamic.
✔ UA not behind NAT: The device sends media according to option Disable NAT (1).

Note: : This option is applicable only to SBC calls. If the parameter is configured to this option, Gateway calls use option Enable NAT Only if Necessary (0), by default.

■ [4] NAT by Signaling Restricted IP = The device identifies whether or not the UA is located behind NAT based on SIP signaling. The device assumes that if signaling is behind NAT that the media is also behind NAT, and vice versa.
● UA behind NAT: The device sends media only when the source of the media packets is the signaling IP address (source of the INVITE). If the 'Media Latch Mode' parameter is configured to Strict, the 'Media Latch Mode' parameter automatically changes to Dynamic.
● UA not behind NAT: The device sends media according to option Disable NAT (1).

Note: This option is applicable only to SBC calls.

For more information on NAT traversal, see First Incoming Packet Mechanism.

'NAT IP Address'

configure voip > sip-definition general-settings > nat-ip-addr

[StaticNatIP]

Defines the global (public) IP address of the device to enable static NAT between the device and the Internet. For more information, see Configuring a Static NAT IP Address for All Interfaces.

Note: The parameter is applicable only to the Gateway application.

[NATBindingDefaultTimeout]

The device sends SNMP keep-alive traps periodically - every 9/10 of the time configured by the parameter (in seconds). Therefore, the parameter is applicable only if you configure the [SendKeepAliveTrap] parameter to [1].

The parameter is used to allow SNMP communication with AudioCodes One Voice Operations Center (OVOC) management platform, located in the WAN, when the device is located behind NAT. It is needed to keep the NAT pinhole open for the SNMP messages sent from OVOC to the device.

The valid range is 0 to 2,592,000. The default is 30.

Note: For the parameter to take effect, a device restart is required.

'SIP NAT Detection'

configure voip > sip-definition advanced-settings > sip-nat-detect

[SIPNatDetection]

Enables the device to detect whether the incoming INVITE message is sent from an endpoint located behind NAT.

■ [0] Disable = Disables the device's NAT Detection mechanism. Incoming SIP messages are processed as received from endpoints that are not located behind NAT and sent according to the SIP standard.
■ [1] Enable = (Default) Enables the device's NAT Detection mechanism.