Westermo MR Series - Manual (Page 374)

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Answering ISDN Calls 10
Westermo routers are capable of answering incoming B-channel ISDN calls with 3 main protocols.
Usually several instances of these protocols exist. This section explains how answering priorities
work for the different protocols.
Protocol Entities 10.1
The following protocol instances are capable of answering an incoming ISDN call:
Adapt
Adapt instances provide rate adaptation protocols such as V.120 or V.110.
LAPB
LAPB instances allow the unit to answer incoming X.25 calls over ISDN. They can optionally
con nect the caller to a synchronous serial port, an asynchronous serial port bound to a PAD,
or switch the call to another interface.
PPP
IP data tunnelled over PPP instances allow remote access to the unit’s IP-based management
fea
tures and also facilitate onward IP routing through any of the unit’s IP enabled interfaces.
The unit will automatically answer an incoming ISDN call if any of the following statements are
true
(subject to the entity MSN, Calling Number and Sub-address parameters being set to their
default
values):
An Adapt instance is bound to an asynchronous serial port (ASY) and the answer ring •
count (S0) for that serial port is set to 1
A LAPB instance has its answering parameter set to On
•
A PPP instance has its answering parameter set to On •
If more than one of these protocols are configured to auto answer then the priority is as follows:
Adapt instances (normally V.120) will take priority over LAPB, which will take priority over PPP.
If an Adapt instance is bound to an asynchronous serial port (ASY port) but the answer ring count
(ATS0) is not set to 1 for that same serial port then Adapt entity will not answer automatically. If
any other protocol entities (e.g. LAPB, PPP or another Adapt instance) are configured to answer
then one of these protocol entities will answer the call. If no other protocol entities are configured
to answer then a repeating RING message will be sent out of the serial port and the RS232 ring
indicator control will be activated. If a terminal attached to the serial port sends ATA followed by
carriage return then the ISDN call will be answered by the Adapt entity and any incoming data will
be channelled out of the serial port and vice-versa.