Westermo MR Series - Manual (Page 375)

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Multiple Subscriber Numbers 10.2
An MSN (multiple subscriber number) is an alternative number provided by the telephone service
pro vider which when dialled will also route through to your ISDN line. It is possible to purchase
several MSNs for an ISDN line. This means that in effect one ISDN line can have several ISDN num-
bers.
Every entity in the router which is capable of answering an ISDN call (Adapt, LABP and PPP) has an
MSN parameter.
A protocol entity’s MSN parameter can be used to:
cause a protocol instance not to answer an incoming ISDN call (if the trailing digits of the •
ISDN number called do not match the entry in this field).
increase the answering priority of an instance (if more than one protocol instance is config- •
ured to answer and the trailing digits of the ISDN number called match the value of the MSN
parameter for a particular protocol instance).
Example
Consider the following:
an Adapt instance is bound to a serial port and ATS0 for that serial port is set to 1 •
PPP instance 0 has answering turned On •
the ISDN line to which the router is connected has two numbers: the main number is 123456 •
and the MSN number is 123789
Normally, because ADAPT has a higher answering priority than PPP, the Adapt instance will answer
when either of the numbers are called. However if the ISDN number dialled is 123456 and 456 is
entered into the MSN parameter of PPP then PPP will answer instead. This will also have the effect
of preventing PPP from answering if any other ISDN number (e.g. 123457) has been called.
This means that whenever 123456 is called the PPP instance will answer and that whenever 123789
is called the V120 instance will answer.
It is possible to connect multiple ISDN devices to the same ISDN line. MSNs can then be used to
allow the different ISDN devices to be dialled individually (i.e. dial the main ISDN number and get
through to ISDN device one, dial the first MSN and get through to ISDN device number two, dial
the second MSN and get through to ISDN device number three, etc.).
Multiple PPP Instances 10.3
It is also possible to configure multiple instances of a particular entity to answer. For example,
PPP instance, 0, 1 and 4 could be configured to answer. In this case provided that none of the PPP
instances are busy, the PPP instance with the highest number will answer first. MSNs can also be
used to ensure that a chosen PPP instance answers the call.
Multiple protocol entity answering instance rules:
ADAPT
The lowest free Adapt instance with auto-answering enabled will answer first.
PPP
The lowest free PPP instance with answering on will answer first.
LAPB
The lowest free LAPB instance with answering on will answer first.