Codec Tieline ViA User Manual page 149

10. Use the on-screen keyboard to enter each number, then tap Done in the top right-hand
corner of the TOUCH SCREEN to add each number.
T
11. ap Save in the top right-hand corner of the TOUCH SCREEN to confirm and store all
entered numbers.
Important Notes:
Directory Numbers and Multiple Subscriber Numbers
Directory Numbers (DN) in North America and Multiple Subscriber Numbers (MSN) in the
rest of the world are simply phone numbers associated with an ISDN B channel, like lines
listed in a typical phone directory. Your Telco will normally supply 2 DN/MSN numbers for
each pair of B channels. However, these numbers may or may not be associated with a
specific B channel.
Often broadcasters prefer to predict which B channel will answer an incoming call to
ensure audio routing is consistent. However, if a DN or MSN number is not entered in the
codec and multiple B channels are available, the codec may use any channel to answer
an incoming call. To ensure calls are routed consistently, enter a DN/MSN number
(without the country or area code) as the DN/MSN for a B channel, then only that
corresponding B channel will answer an incoming call to that number. Programming
DN/MSN numbers for each B channel allows the codec to ignore calls without matching
DN/MSN numbers. This is the best way to answer calls from codecs in a predictable
manner.
SPID Numbers in North America
ISDN relies on an initialization procedure for associating Service Profiles with specific
terminating equipment (e.g. your audio codec) rather than lines. In the US Telcos assign
a Service Profile ID (SPID) number which assists in identifying different ISDN services
across the network. Your Telco must provide a SPID for each B channel you order when
connecting over US-Nat or US-AT&T networks in the US. A SPID is not required when
using the AT&T PTP protocol.
Typically, each ISDN BRI service in the US will have two SPIDs and these must be
entered correctly. When you enter a SPID into your codec and connect it to an ISDN line,
an initialization and identification process takes place, whereby the terminating equipment
(your codec) sends the SPID to the switch. The switch then associates the SPID with a
specific Service Profile and directory number.
© Tieline Research Pty. Ltd. 2020
ViA User Manual v3 149