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Quick Start Instructions MultiVOIP User Guide
74
(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 ➠
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