Introduction To E1 And T1; Overview; E1/T1 Voice Functions - 3Com MSR 50 Series Configuration Manual

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Introduction to E1 and
T1

Overview

E1/T1 Voice Functions

E1 T1 C
AND
This section covers these topics:
"Overview" on page 2309
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"E1/T1 Voice Functions" on page 2309
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"E1/T1 Interface" on page 2310
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"Features of E1/T1" on page 2311
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Plesiochronous digital hierarchy (PDH) system includes two major communications
systems: ITU-T E1 system and ANSI T1 system. The E1 system is dominant in
Europe and some non-Europe countries. The T1 system is dominant in USA,
Canada and Japan.
E1 and T1 use the same sampling frequency (8 kHz), PCM frame length (125 ms),
bits per code (8 bits) and timeslot bit rate (64 kbps). They differ in these aspects:
E1 adopts A law coding/decoding of 13-segment but T1 adopts m law
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coding/decoding of 15-segment.
Each PCM primary frame of E1 contains 32 timeslots but T1's contains 24
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timeslots. Each PCM primary frame of E1 contains 256 bits but T1's contains
193 bits. Therefore, E1 provides 2.048 Mbps bandwidth but T1 provides 1.544
Mbps bandwidth.
E1/T1 voice implements VoIP on E1/T1 line. To this end, your router must have
E1/T1 voice interfaces and be configured with functions required for transmitting
voice over E1/T1 lines.
The physical interfaces carrying E1 and T1 voice interfaces are respectively VE1 and
VT1 interfaces.
When E1/TI is adopted for voice transmission, PSTN exchanges and routers are
connected by E1/T1 trunks, as shown in
ONFIGURATION
Figure 670.