Panasonic KX-NCP500 Programming Manual

Also see for KX-NCP1000: Brochure & specs Specifications Installation manual Guide Networking guide

Contents

Panasonic KX-NCP500 Programming Manual Manual pdf 7 page image

• VoIP communication using the V-SIPGW16 card may deteriorate depending on the network conditions.DNS (Domain Name System)A DNS server normally provides the name resolution service for your computer. As domain names arealphabetic, they are easier to remember. The Internet, however, is based on IP addresses. Therefore, everytime a domain name is used, a DNS server must translate the name into the corresponding IP address, andvice versa. For example, the domain name www.example.com may be translated to 192.0.34.166. If one DNSserver does not know how to translate a particular domain name, it asks another one, and so on, until thecorrect IP address is returned.NAT (Network Address Translation) TraversalWhen NAT/NAPT (Network Address Port Translation) is enabled, the router translates a local IP address fromthe PBX into a global IP address. However, the router with NAT enabled does not translate local IP addressesstored in SIP messages into global IP addresses.Therefore, the address which the SIP Server recognizes as the destination IP address to reply to is actuallythe local IP address of the PBX, not the global IP address of the router. Therefore, if the SIP server receivesa SIP message from the PBX and sends a message back to the PBX using the address stored in the SIPmessage, the packet information will not reach the PBX.STUN Servers function to solve the global IP address problem under certain NAT conditions, for example, incase of full duplex communication. A STUN Server, used alongside the SIP Server, finds out the global IPaddress of the router with NAT enabled. With the STUN feature enabled, the packet information sent by theSIP Server is able to "traverse" NAT and reach the PBX.The settings can be configured to specify whether to enable the NAT Traversal feature for each ISP/ITSP. Inaddition, the NAT Traversal method can be selected from "STUN" and "Fixed IP Address" (refer to3.3.1 Main, NAT Traversal).The V-SIPGW16 card may require the NAT Traversal feature to be enabled to connect to the WAN via a router.The following diagram illustrates how VoIP communication is enabled between the V-SIPGW16 card and theSIP Server (SIP Receiver) via a router with NAT enabled.Document Version 2011-10 Programming Manual for Virtual SIP CO Line Card 71.1 Information about IP Telephony Service