Incorrect protocol settings either result in an immediate termination of the connection or prevent the ISDN connection from being established in the first place (error message: "The computer you are dialing in to is not answering.").
Setting modem registers for ISDN B-channel protocols and
PPP
The virtual modem ISDN Internet (PPP over ISDN) is set by default to HDLC and
PPPover ISDN according to RFC 1618. If a different configuration is required by your Internet provider, you can change the
•S31=0X.75 protocol
•S31=1HDLC protocol (default)
•S31=2V.110 protocol
•S31=7V.120 protocol
The registers ”S41”, ”S42” and ”S43” can also be used to set the B1, B2 and B3 protocol layers individually. However, this is not necessary in most cases.
The PPP protocol variant used can be configured using register "S51":
•S51=0asynchronous PPP ("modem style", RFC 1162)
•S51=1synchronous PPP ("PPP over ISDN", RFC 1618)
Authentication
For PPP connections, the
Some Internet providers (including many universities, etc.) use the calling line identification transmitted over the ISDN D channel in addition to or instead of the user name and password. The next section explains how the virtual modem must be configured to transmit the ISDN
ISDN D-channel
Entering the ISDN
Using the registry command S49=<multiple subscriber number>any multiple subscriber number (MSN) from the block assigned can be specified for transmission in the D channel. The block of numbers for your line is assigned by the network provider.
