NETGEAR XM128 ISDN manual Answering Async to Sync PPP calls, Multilink PPP

Reference Guide for the Model XM128 ISDN Digital Modem

Answering Async to Sync PPP calls

There is no need to configure the ISDN mode to the protocol of an incoming call. If it is set to auto-answer or an answering command is issued, the Model XM128 modem determines the correct protocol to use by examining the data coming in from the remote site. One exception is when the ISDN data call is carried through a Speech bearer. In this case you would need to set up an MSN for the phone number of the calling party. To do this, use the command AT&ZI3=xxx; where xxx is the number from which the call originates.

For the Model XM128 modem to automatically answer incoming calls, you need to set S0 to a value greater than 0 (i.e. ATS0=1). The Model XM128 modem answers the call and uses asynchronous to synchronous conversions to and from the DTE. If S0 is not set (S0=0), the DCE reports RING and also makes an audible ring notification.

Multilink PPP

Multilink PPP (MPPP) is a protocol that allows virtual bundling of the two B channels allowing connection speeds of 128Kbps. MPPP support is a standard feature of the Model XM128 modem.

Making a call using Multilink PPP

A Multilink PPP connection is initiated at the calling site when ATB40 (B channel protocol HDLC PPP) has been selected and the Multilink PPP mode has been enabled by an AT&Jn command:

AT&J0 (disables Multilink PPP)

AT&J1 (enables Multilink PPP in answer mode only)

AT&J2 (enables Multilink PPP in call mode only)

AT&J3 (enables Multilink PPP in both call and answer modes)

By default, the Model XM128 modem dials the same number for both Multilink PPP connections. If the destination you are dialing requires two different telephone numbers to establish a two channel Multilink PPP connection, then the following command can be used:

ATDIphone_number_1+phone_number_2

The phone numbers of the destination are determined by the commands: phone_number_1 and phone_number_2 are the phone numbers of the destination.

If the destination refuses the Multilink PPP during the Link Control Protocol (LCP) negotiation, a single B channel PPP connection is established. The connection message is the same whether the Multilink PPP connections have been established or not.

Async to Sync PPP 5-3