Switched, Dedicated, and Mobile Access Lines: ADSL, ISDN, GSM, GPRS
Switched Access Lines
Switched access lines are those that need to establish a call between two endpoints for communication, i.e., the lines connecting each central pole from origin to destination, e.g., a phone call. The optimization of these lines requires stations to use coral switching, i.e., the two ends together with their mechanisms.
Land Lines
Switched telephone networks are guided by a physical means, usually a twisted-pair cable with two or four copper wires. RTC serves voice and data transport.
Definition of modem: performs the operation of modulating; a digital signal converts to analog for the computer and brings it to RTC, demodulates and converts the analog signal into digital from RTC and leads it to the computer.
Services:
- Basic telephone service
- Supplementary services
- Cards
- Telephone terminal
- Public use telephony
- VPN
- Voice over IP service
- Voice conference
- Internet access
Advantages:
- Easy installation and setup
- Low maintenance cost and utilization
- Free internet access (minimum fee)
Disadvantages:
- Low access speed
- Requires specific hardware
- Software incompatibility of service
- Analog system
Internet connection: The connection is established through a call to the number of the central ISP assigned to us.
ISDN
Normalizes ISDN digital network and integrates the available services. Types:
- Broadband: speeds above 2MB/s, TV, and video conferencing
- Narrowband: uses dial-up connection
- Basic-access: low bitrate
- Primary Rate: medium bitrate
Services:
- Lines
- Equipment
- PC cards
- Video conferencing solutions
- Service migration as a functional
- Maintenance
- Software download for discontinued equipment
Advantages:
- Easy installation and configuration of the adapter
- Higher speed access
- Support services
- Digital
- Free internet access (fee)
Disadvantages:
- Higher cost of maintenance and utilization
Internet connection: Is equal to the RTC, using a modem.
GSM
GSM (Global System for Mobile Communications) is a standard that dominates in Europe. It is used for digital mobile phones. The line is not connected to the phone but to the SIM.
Services:
- Better voice quality
- Low-cost mobile units operational
- Procurement and service
- High security
- International roaming
- Personal terminals and low-power portals
- New services and network facility
Frequency bands:
- GSM 900
- DCS-1800
- PCS-1900
Advantages:
- Allows data transmission
- Security guarantees
- Offers services related to ISDN
- Low prices
Drawbacks:
- Loss of coverage
- Maximum number of users
Internet connection: From the mobile using the WAP protocol, to connect another device to the Internet.
GPRS
GPRS (General Packet Radio Service) is a technology that uses the GSM network to optimize the work of data.
Advantages: Compatible with voice systems; can send data and voice simultaneously.
Dedicated Access Lines
Dedicated access lines are exclusive lines that only their full-time subscribers use. The difference with dial-up lines is that all lines are active as a solution that is always online, i.e., transmission capacity is available permanently.
Characteristics of Terrestrial Communities
The ADSL over PSTN networks — ISDN already in place in our country — will be able to expand the bandwidth, and thus the speed of access and the number of services. On the other hand, there will be an emerging technology that is still being tested, such as the connection via electrical cable (PLC), which uses power lines to carry the data signal to the plant.
ADSL
ADSL (Asymmetric Digital Subscriber Line) uses the current loop twisted-pair copper to turn it into a digital line at high speed, thereby achieving faster speeds and being known as a broadband Internet connection. ADSL ranges from 24 kHz up to 1104 kHz to transmit data signals in both directions. Basically, it consists of four elements:
- ADSL Remote Terminal Unit, which is a modem located at the user’s home.
- The Central Terminal Unit ADSL, a modem located in the central subscriber.
- The user splitter. The received signal is divided into two: one for conventional telephone (voice) and one for ADSL (data).
- On the central splitter, the signal is separated, sending the voice to PSTN, transmitting data by another independent system to this.
Definition of Splitter
A splitter is a device to separate the signals, which consists of a set of two filters. The first is called a low-pass filter that passes low-frequency signals, i.e., voice, and the other is the high-pass that lets high-frequency signals, i.e., ADSL data, pass.