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MultiVOIP User Guide Quick Start Instructions
71
(b) access codes. There are digits (PSTN access codes) that must be
dialed to gain access to an operator, to access the publicly switched
‘long-distance’ calling system(North America), to access the publicly
switched ‘national’ calling system (Europe and elsewhere), or to access
the publicly switched ‘international’ calling system (worldwide).
There are digits (PBX access codes) that must be dialed by phones
connected to PBX systems or key systems. Often a “9” must be dialed
on a PBX phone to gain access to the PSTN (‘to get an outside line’).
Sometimes “8” must be dialed on a PBX phone to divert calls onto a
leased line or to a voip system. However, sometimes PBX systems are
‘smart’ enough to route calls to a voip system without a special access
code (so that “9” might still be used for all calls outside of the building).
There are also digits (special access codes) that must be dialed to gain
access to a particular discount long-distance carrier or to some other
closed or proprietary telephone system.
(c)
local exchange numbers. Within any calling area there will be many
local exchange numbers. A single exchange may be used for an entire
small town. In cities, an exchange may be used for a particular
neighborhood (although exchanges in cities do not always cover easily
discernible areas). Organizations like businesses, governments,
schools, and universities are also commonly assigned exchange
numbers for their exclusive use. In some cases, these organizational-
assigned exchanges can become non-localized because the exchange is
assigned to one facility and linked, by the organization’s private
network, to other sometimes distant locations.
(d)
specialized codes. Some proprietary voip units assign, to sites and
phone stations, numbers that are not compatible with PSTN
numbering. This can also occur in PBX or key systems. These
specialized numbers must be handled on a case-by-case basis.
3.
Knowing When to Drop Digits. Example
When calling area codes and
access codes are used in
combination, a leading “1” or “0”
must sometimes be dropped.
Phonebook Entry Æ
Area code for Inner London is
listed as “0207.” However, in
international calls the leading
“0” is dropped.
International
Access Code
U.K.
Country
Code
Leading Zero
Dropped from
Area Code