Connection Type

A: FXS port of VG3300 Series

B, C: SIP Device (VG3300 Series, other brand SIP gateway. SIP phone...), Normal PSTN phone call (special condition is described below)

Call waiting function works only on SIP call. So PSTN call works when it is transited as SIP call. If Inbound transit call is configured on VG3300 (please refer to 10.9 Make Inbound Transit Call), then Call Waiting function is available when user dials the SIP number of this VG3300 gateway itself. If no inbound transit call function is configured, it is impossible to do call waiting function.

11.7. Target the Media (RTP)

For the SIP call passing through NAT, it is possible that the media would not deliver properly; owing to the RTP contact information (IP address, port number) is different from original RTP packet. This function selects different contact information for VG3300 to send RTP Packets to other SIP device within far-end NAT. It designates whether to use the source contact information from the UDP/IP header (Symmetric RTP) or the contact information specified within the packet (SDP) when the gateway send RTP packet

Web Folder：ADVANCED\SIP COMMON, Default Value is SDP

Example 1: Via Symmetric RTP

The source contact information (IP, port number) of RTP packet is IP: 61.222.217.30, port number:

10000, but the SDP in the packet is IP: 10.13.6.18, port: 4000. In this case, please Use

Symmetric RTP

VG3300 Series (192.72.83.23, port: 10000)

61.222.217.30 port: 10000

SDP in Packet

10.13.6.18Network port: 4000

VG3300 tries the contact information from SDP first (IP:10.13.6.18, port number: 4000). If VG3300 finds that the contact information from SDP is different from the source contact information, then it will try the source contact information, as the example above, use IP:61.222.217.30, port number:10000. It makes SIP call successful.

Example 2: Via SDP (Default)

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