Telephone SystemBy : Warsun Najib

Telepon System Concept Telephone network is often called as PSTN (Public Switch

Telephone Network) Telephone Device Central Office (CO)

suatu istilah untuk menggambarkan pusat jaringan telepon (dalam suatu kota). Tugasnya menyediakan daya untuk telepon, me-routing panggilan, merekam tagihan telepon, dsb.

Trunk (E1) Link/kabel between CO to other CO

Local Loop Pasangan kabel telepon yang terhubung antara central office dan pesawat telepon rumah (kantor).

Switch Perangkat yang me-route komunikasi ke bagian (tempat) yang lain.

Pada awalnya, switch terbuat dari banyak switch-switch mekanik Saat ini, mayoritas switch adalah elektronis, bahkan digital. Digital switches lebih reliable, dan menawarkan banyak keuntungan

Distribution Network MDF Rumah Kabel

Telephone Set

Standby : Hoook switch is on position 1, Idc from CO does not come, Ringing signal (ac) can activate Bell

Busy : Switch is off-hook (hook-switvh on position 2),

Hibrid•Pemisah mic dengan speaker•Penekan nada samping

Dialer

Mic

Speaker

Bell

Hook Switch

1

2

H D

Telephone : Off-Hook / Busy

Side Tone

Dialing System DTMF (Dual tone multi frequency) Rotary Switch

Dual Tone Multi-frequency

1 2 3

4 5 6

7 8 9

#0*

Baris 1 [697 Hz]

Baris 2[770 Hz]

Baris 3[852 Hz]

Baris 4[941 Hz]

Kolom 1[1209 Hz]

Kolom 2[1336 Hz]

Kolom 3[1477 Hz]

Periode T > 100 ms depend on how fast finger push the button (normally 250 ms)

Digit ‘1’ Digit ‘6’

T T

i(t)

t

DTMF

space

7

6

5

4

3

21

0

89

Dialing : Rotary Switch‘1’ one stop pulse‘2’ two stop pulse‘3’ three stop pulse…‘0’ ten stop pulse

T/3 T :100 ms ≥ 4T

‘3’ ‘2'

i(t)

t

space

Dial a numberOff-hook

0

Rotary switch dialing system

Subscriber link signal (Link Voltage)

Volt100

50

0

-50

-100

-150

On-hook Off-hook

Dialing pulse

voice

Bell, ringing voltage

20 Hz, 90 Vrms, 2 s on, 3 s off

Incoming

Outgoing1-2 V

ingoing0,5-1 VΔv: 48 V

ΔI: 18 mA

I:16-20 mA, 6-8 V

48 V

register

Switching Device

Controller

trunk

SLIC

Pengisyaratan

SLIC

SLIC

trunk

Pengisyaratan

Switching Element

Controller can be : •Sentralized•Distributed at signaling and switcing Device

SLIC : Subscriber Line Interface Circuit

To/from other CO

Central Office

Switching SystemStep By Step,Each digit activates directly one switching-level, except the last 2 digit usually connected to 2-dimension switch

3054

3 0 5 4

Call Finder

Switch level 1

Switch level 2

Switch level 3

Switch level 4

Illustration of Call Switching

Common Control Each digit of dialed number is first stored

in a register at CO, then if the destination number is not busy, call is routed to the phone.

Caller lift handset / off hook

CO find the available link

Get a link

CO send dial-tone to caller

Caller dial the destination number

Switching Process of Telephone Call

Yes

No

CO make switching process

Is dialed numberfree (not busy) ?

CO send:•Ringing signal to dialed phone•Ringing tone to caller phone(tuut – tuut…..)

CO send busy tone to caller phone

Call dropCalled phoneOff hook

Call success

yes no

yes

No

Voice SignalingNama Signal Kegunaan Off-hook Memberitahu CO bahwa user

ingin melakukan panggilan Dial tone Memberitahu user bahwa CO

sudah siap melayani (ready) Ringback tone Memberitahu user bahwa

telepon tertuju sedang berdering

Ringing voltage Tegangan tertentu yang dikirim untuk membunyikan bel

Busy signal Memberitahu user bahwa telepon tertuju sedang sibuk

On-hook Memberitahu CO bahwa user

CO

Private Branch eXchange...

Common Subscriber

PBX90XXXX

m ext-link

.

.

.

Operator

n main link

22012202

1302

PBX is categorized: PMBX private manual branch exchange

Both intern and extern call is handled by an operator PABX-private automatic branch exchange

Intern call is automatic Extern call

Automatic if the device has DID (direct inward dialing) Via operator If device does not have DID

If n >1 (link between co-pbx) User call via one number if PABX has hunting system User can call via n different number if PABX doesn’t have

hunting system. Advantage of PBX

Cost Probability of success call

Numbering System Open System Close System

Network from CO to Subscriber

LE-

MDF CCP CCP

DPDP

DP PBX

Primary network

Secondary network

MDF 2000 pairsCCP 50 pairsDP:10 pairs

MDF,CCP,DP are in a form of cable switching terminal

Network Between LE

LE LE LE

Toll Central

Toll Central

Toll Central

Regional Central

LE LE LE

Toll Central

Toll Central

Toll Central

Regional Central

yk1 yk2 yk3

One local area