IOL Proudcts
Dial-up connection

Integrated Services Digital Network is an all-digital communications line that allows the transmission of voice, data, video, and graphics, at very high speeds, over standard communication lines.

There are two ways to provide the ISDN services to the customers. These are:

Basic Rate Access Interface (BRI) provides:

two full-duplex 64 kbps bearer (B) channels
one full-duplex 16 kbps D channel

Primary Rate Access Interface (PRI) consists of:

up to 23 (for T1 lines) and
30 (for E1 lines) 64 kbps B channels

The main transport medium for ISDN is the T1 /E1 digital line. The T1 /E1 interfaces are used to transmit digital voice and data at a maximum 1.544 Mbps / 2048 Mbps rate. E1 and T1 belong to the physical layer in the OSI reference model, thus Layer 2 technologies such as ATM and FR are carried over it. A T1 /E1 line connects two points: in one point the information is multiplexed and in the second demultiplexed.

Advantages of digital telephony are:
Cable Broadband
DSL Broadband
Radio link
Domain registration
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Prepaid users
Check usage
Change password
Customer Support
Free Home Delivery
• More efficient because multiple voice channels are multiplexed and
transmitted over a common transmission path.
• More economical when compared to the number of equivalent analog lines that
would be required.
• More reliable in that repeaters maintain the integrity of the digital signals over
long distances.
• This technology is better suited for high speed and high reliability digital dial-up data and voice transmission. Most of the world’s largest ISPs including AOL and MSN of USA, BT of UK use the E1/T1 technology for their high speed digital dial-up data and voice services. All the mobile telephone operators in Bangladesh also use the E1 for their BTTB connectivity.
The following topics provide information about the major aspects of T-1 / E-1 technology:
• Digital Telephony
• Digital Voice
• Basic Time Division Multiplexing
• T-1 and E-1 Applications
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