ZyXEL Communications 400, User Manual

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Gateway 400 User Guide | Configuration
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5.5 Telephony
This screen dialog shows an overview of statuses of the telephony connections. The term VoIP
(Voice over Internet Protocol) always refers to Internet telephony.
Under Telephony , the status is shown as “Available” or “Not available”.
Under Internet Telephony , you can view further details for each connection. “VoIP Accounts” on
page 27 describes how to configure and edit the Provider , Call number , Name and Status .
The status should be displayed here as a green check mark , followed by information about the
time of activation.
If a red cross appears instead, first check whether the VoIP account was disabled as described in
the section “VoIP Accounts” on page 27 . If all VoIP accounts are affected, check the DSL connection.
If the error occurs for individual VoIP accounts, ask your VoIP provider (Internet telephony provider)
to check the configuration of the
“VoIP Accounts” on page 27 or the status of the VoIP account.
5.5.1 General
This screen dialog allows you to make various settings for the telephony mode.

Overlap Dialing
By default, SIP uses en-bloc dialing. This dialing method first collects all the digits of the number to
be dialed and then transmits the entire number en bloc. Alternatively, the Gateway 400 provides
the option of
Overlap Dialing according to RFC 3578, which tries to accelerate connection setup by
attempting to dial partially entered, incomplete numbers while digits are being entered.
If the option Overlap Dialing is enabled, the additional option Enable fallback to normal dialing will
be available. This option can be used to temporarily enable en-bloc dialing if the connection setup
fails using overlap dialing.

Configuration of incoming VoIP calls
For incoming calls, some VoIP providers (Internet telephony providers) transmit the destination call
number in the “To-Header” line of the SIP protocol instead of the “Request-Line”.
With this option, you can ensure that the destination call number is analyzed correctly and forward-
ed in the Gateway 400 exactly as specified in the transmitted data.

International Call Prefix
If the VoIP account (see VoIP Accounts on page 27 ) was configured with the country code, the call
numbers will also be transmitted with the country code. Here you can select the Call Prefix to be
used for outgoing call numbers. Similarly, the string selected here is also expected as a prefix for in-
coming calls.

Number format of incoming calls
Under Number Format , you can select the format in which the call number is transmitted for incom-
ing SIP-to-ISDN connections:
Unknown The call number is transmitted 1:1 from SIP to ISDN
Subscriber Only the call number (without the area code) is transmitted
National Both the area code and the call number are transmitted
International The country code, the area code and the call number are transmitted