Aastra OpenCom X320 User Guide - Page 91
E-mail, 7.6.4 NAT, NAT
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Configuration Examples Useful Information on Internet Access ■ The OpenCom X320 can block access to certain Web pages by means of filter lists. 7.6.3 E-mail One of the most important services in the Internet is e-mail. E-mails are buffered in individual e-mail accounts on a mail server. Mail servers are operated by ISPs for example. With the OpenCom X320 you can set up one or more e-mail accounts for every user account configured on the OpenCom X320. These e-mail accounts are then checked at regular intervals. If there are new e-mails in an e-mail account, and the OpenCom X320 has been configured for this function, the user specified in the OpenCom X320 user account is notified of the new e-mail on his system terminal. OpenPhone 6x/ OpenPhone 7x and OpenPhone 2x system terminals can also display information such as the sender or the subject of the e-mail. 7.6.4 NAT Network address translation (NAT) is activated on accessing the Internet (ISP). You require this feature in order to translate internal IP addresses to valid external IP addresses. This has three important consequences for Internet access: ■ Several workstations can share a single Internet access. You do not require a LAN access, only a single account with the Internet service provider. ■ The IP addresses used in the LAN are translated into IP addresses valid worldwide. So you require no such addresses for your LAN. ■ Only IP connections triggered from a workstation can be established. Consequently, while you can call up Web pages from a workstation, you cannot install a Web server visible in the Internet on a workstation. Certain protocols cannot be used when NAT is being used. This affects protocols with the following properties: ■ IP addresses are transported in the useful load, e.g. NetBIOS over IP or SIP. ■ The protocol requires an active, inward-directed connection establishment, e.g. ICQ. 89