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Sources

Exchanges the control information

associated with the caller.

SIGNALING SYSTEM (SS7)

Signal Pathways

A dedicated signaling channel is

maintained alongside an active voice

channel where the conversation lives.

COMMON CHANNEL

SIGNALING (CCS)

Analog signals are transmitted

through electrical wires, resistors

and capacitors.

EARLY TELEPHONE

Large transmission lines are used

for long-distance calls.

PSTN: Publicly Switched Telephone Network

TDM: Time Division Multiplexing

Time slots

are assigned to

single users

TRADITIONAL TELEPHONY

ACROSS PSTN* & TDM*

Single unbroken line from telephone

A to telephone B in classic PSTN.

CIRCUIT SWITCH NETWORK

Data stream is split into small

packets that are sent on router-

determined pathways.

PACKET SWITCHED

NETWORKS (PSN)

Digital signals are transmitted by

passing 8000 analog samples through

a computer chip.

MODERN TELEPHONE

Pressable phone numbers emit high

and low-frequncy sine waves.

DUAL TONE MULTI

FREQUENCY (DTMF)

Life of a Call

MODERN TELEPHONY

TECHNOLOGY

Signal Transmission over the Ages

Voice & Data

Once Separate

Computer files and voice signals are

transmitted over the same wires.

Voice Data

Digital Subscriber Line (DSL)

This is accomplished by keeping the

basic PSTN infrastructure and placing

data transmission on top of it.

OLD UNIFICATION METHOD

Voice Over Internet Protocol (VoIP)

Voice, data, and video are transmitted

over networks in packets (PSN) rather

than dedicated timeslots (TDM).

NEW UNIFICATION METHOD

Noise is additive and

therefore vulnerable to

interference and degredation

Noise is regenerated

through sampling and

therefore more clear

Now United

Signaling Channel

Voice Channel