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An PPP interface can be configured here


PPP Interface

  • Enable: Enables/disables the interface. The PPP interface is only displayed in the PPP State overview page if it is enabled.
  • Connection Port: For PPP connections using ISDN channels, you select one of the ISDN interfaces (PPP, TEL, BRI, PRI) here. This concerns only devices with an ISDN interface. However, PPTP (VPN) and PPPoE (DSL) connections using the Ethernet interface (ETH) are also possible.
  • Descriptive Name: A descriptive name for the interface can be entered here. This name is used for the overview in the PPP State submenu (see chapter entitled "Configuration/IP/PPP-State").
  • Bandwidth: By specifying a particular bandwidth, the transfer rate for a connection can be restricted and the available network bandwidth is optimally allocated. This is necessary, since for an upstream, the available bandwidth may be lower than required. Packets that exceed the maximum available bandwidth would be discarded. If a bandwidth is specified, packets that exceed the maximum available bandwidth are not sent at all.
  • Maximum transfer unit (Bytes): Overrides the default value for the maximum size of a packet to be sent over the interface. This may be necessary to overcome problems with certain service providers. The default MTU values are:
  • PPPoE - 1492
  • PPTP - 1436 (since V6 SR1 - hotfix 3, 1500 before)
  • ISDN - 1500
  • IP Address for Remote Party: Assign a local IP-Address to the remote party in order to integrate it in the local network.
  • Auto dial after boot: Automatically establish the dial-up connection at start-up time and every time when the connection is lost.
  • Restart Time (hour:min): If Auto dial after boot is checked an automatic restart of the connection can be requested. The connection is automatically dropped and dialled again at the given time each day. A restart is performed only if the box has got a valid Time from a NTP server. (available since V6 SR2 - hotfix 4)
  • Allow inbound connections: If the server is configured as a PPP server, a checked check box allows PPP dial-up connections to the device (inbound).
  • No DNS on this interface: When a PPP connection to the remote party is set up, an attempt is always made as standard to resolve the name of the remote party to an IP address via DNS. Here, there is always the risk, however, that there may be several PPP connections that use the same IP-Address (for example, As a result, a name resolution would take place once only, and the data packets sent to a different name with the same IP-Address are lost.
  • Exclude interface from NAT: With this setting, a particular interface can be excluded from NAT (Network Address Translation), should NAT be enabled (see chapter entitled "Configuration/IP/NAT").
  • No IP Header Compression: The VoIP devices support the compression of voice data along the PPP link using the RTP header compression method (RFC 2508, RFC 2509). This drastically reduces the required bandwidth for VoIP calls. To suppress this, the No IP Header compression check box must be enabled.
  • Adapt to Cisco PPP peers: Try the Adapt to Cisco PPP peers option if a Cisco router is used at the remote location and problems arise in the transmission of voice data.


The PPP protocol allows reciprocal authentication (inbound/outbound). Generally speaking, for inbound connections, only the inbound authentication is required, for outbound connections, only the outbound authentication. But it can also happen that an authentication is required both from the client and from the server.

  • Outbound User / Password: Required for outbound connections. For example, the name of the DSL provider or the DSL user ID of the remote party (,, or the Inbound User / Password of the remote party.
  • Inbound User / Password: Required for inbound connections. For example, the Outbound User / Password of a different gateway.


Here, the interface can be configured as a PPPoE client (for example, for DSL).

  • DSL Provider (Access Concentrator): The DSL modem name. Since several modems can occur in a network, a broadcast is sent for identification.


This operating mode applies for inbound and outbound calls. The PPTP (Point-to-Point Tunnelling Protocol) implements private VPN connections via the Internet or other networks operated with the IP-Protocol. PPTP connections are always dial-up connections. An IP-Address is dialled. Authentication is performed by means of user name and password. In addition, the transferred voice data can be encrypted with MPPE (Microsoft Point-to-Point Encryption). The prerequisite, however, is that the remote party also supports this method. If MPPE was enabled, this may result in a delay in voice transmission. If quality losses of this kind occur, a decision has to be made between security or voice quality. The innovaphone devices can dial into a remote PPTP server as a PPTP client, as well as provide a dial-in point themselves.

  • Server Address: The IP-Address of the PPTP server. If the device itself is to play the role of a PPTP server, then no Address has to be entered here.
  • Route to Interface: Here, connection setup inquiries can be forwarded directly to a particular interface. For example: ETH0-1, PPP0-31.
  • Enable MPPE Encryption: Enables the Microsoft Point-To-Point Encryption Protocol. MPPE (RFC 3078) uses the RSA RC4 algorithm.
  • Stateless Operation: Here, the key is modified after every transferred packet.
  • 40-Bit Encryption: Enables the encryption with a 40-bit session key.
  • 128-Bit Encryption: Enables the encryption with a 128-bit session key.


  • Link Configuration: The ISDN interface configuration can be performed here. The PPP interface can be configured here for inbound and for outbound calls.
  • Link type: Four different link types can be selected.
  • Singlelink (64k) - A connection via a B channel.
  • Multilink (128k) - A connection via two bundled B channels. Provides double the transmission speed.
  • Permanent B1 - Uses the B1 channel exclusively.
  • Permanent B2 - Uses the B2 channel exclusively.
  • Local Subscriber Number: The Local Subscriber Number, in the case of inbound dial-up connections, is the call number (MSN) under which incoming calls are to be accepted.

The Local Subscriber Number, in the case of outbound dial-up connections, is the outgoing call number (MSN) to be used for the call.

  • 2nd Local Subscriber Number: If Multilink is used, a different call number can be used for the second channel of the PPP remote terminal being called. The entry field can be left empty if the same call number as for the first channel is to be used.
  • Outbound Connections: Here, the ISDN interface can be configured for outbound PPP dial-up connections.

Called Party Number: The call number (MSN) to be used for the outgoing call.

  • 2nd Called Party Number: The call number (MSN) to be used for the outgoing call on the second B channel.
  • Inbound Connections: Here, the ISDN interface can be configured for inbound PPP dial-up connections.
  • Calling Party Number: By specifying the Calling Party Number, the acceptance of incoming calls can be restricted to this one call number. If the entry field is left empty, all data calls are accepted on the selected ISDN interface(s).

IP Routes

Static routes for the PPP interface can be configured here. This is required, since no routing protocol is used.

  • Network Address: The network address of the new route being added.
  • Network Mask: The network mask of the new route being added.
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