What is an Expandable Cordless Phone?

Cordless telephone service (cordless telephone service) is a type of telephone service that uses wireless channels instead of telephone cords to enable users to implement mobile calls within a limited range. It is a radio communication service.

Cordless telephone service (cordless telephone service) is a type of telephone service that uses wireless channels instead of telephone cords to enable users to implement mobile calls within a limited range. It is a radio communication service.

Chinese name

Cordless telephone service

Foreign name

cordless telephone service

Application area

Telephone service, radio communication service

Overview of the development of cordless telephone business

Shenzhen first launched the digital cordless telephone CT2 system on August 28, 1992. By the end of 1992, more than 490 public base stations had been completed, equipped with 1,200 pairs of local telephone trunk lines, and more than 8,500 users had been developed. The system plans to build 5,000 public base stations, 15,000 pairs of trunk lines, develop 100,000 users, and vigorously develop home base stations to expand coverage and achieve CT2 multifunctional services. Compared with mobile phones, digital cordless phones have less investment and lower costs, and have better development prospects.

Cordless phone service business description

The cordless telephone service means that after the user owns the cordless telephone landline and handset, first connect the landline to the fixed telephone line. When the handset is within the coverage of the wireless signal of the handset, the handset establishes a wireless signal connection with the handset. Phone use, inbound and outbound are PSTN numbers, and the handset can also use its Lingtong phone number to communicate through the fixed telephone line connected to the landline; The handset is used as an ordinary smart phone, and communicates through the smart phone public network.

When a Smart Phone is used as a cordless phone handset, there are two ways:
Basic cordless mode Within the coverage of the wireless signal of the base unit, the handset can only be used as a cordless handset of the base unit, which has the same function as the ordinary cordless handset. The basic cordless method does not require network side cooperation.
Super cordless mode In the coverage area of the wireless signal of the landline, the handset can call out through the fixed telephone line connected to the landline with the Lingtong number as the calling number, and can also answer the call to the Lingtong number through the fixed telephone line connected to the landline, so as to maintain the Lingtong. Mobile phone usage. The super cordless method requires the cooperation of the network side.
In the super cordless mode, the handset has two login modes, namely a long-term login mode and a temporary login mode.
Long-term registration of the handsets. The handsets that use the long-term login mode must perform the code pairing operation through the landline and the handset. After the code is matched, the handset and the handset establish a long-term relationship. When the handset enters the coverage area of the handset, it can automatically log in to the handset. .
Temporary login handsets The handsets that use the temporary login mode need to be registered through the Smart Phone when the temporary login mode of the landline is turned on. After registration, a temporary association is established with the corresponding landline, which only has basic call functions.
The handset can use two methods when calling out through the PSTN line, namely, the smart mode or fixed line mode:
Smart phone mode In this mode, the outgoing caller number is a smart phone number.
Fixed telephone mode In this mode, the calling number is the landline fixed telephone number, which is equivalent to an ordinary cordless telephone.
If the landline's fixed telephone line is busy when the handset calls out, the handset will immediately call out this call automatically through the PHS public network (requires PHS public network signal coverage).
A Lingtong mobile phone can be used as a handset of multiple landlines at the same time, such as a handset of a landline in a home and a handset of an office landline.

Cordless telephone service business types and communication methods

There are two types of cordless phones: analog and digital.

The analog cordless telephone service appeared in the mid 1970s, and is mainly designed for telephone users to solve the problem that the telephone cannot move freely indoors, also known as CT0 or CT1. The system consists of a telephone main unit, one or several cordless auxiliary units, and the main and auxiliary units are connected through an analog wireless link. The user can hold a cordless auxiliary unit to move within a certain range of the room. The analog cordless phone has poor voice quality, confidentiality performance and anti-interference ability, but the technology is simple, the cost is low, and the development is rapid.

Digital cordless phone CT2 appeared in the United Kingdom in 1989. It overcomes the shortcomings of CT0 and CT1, and extends the application range to the outdoors. The CT2 system consists of a network management center, a billing system, a base station and a mobile phone. The base station and the local telephone network are connected by a trunk line, and no switching equipment is required. Base stations are divided into public base stations and home base stations. As long as a user has a CT2 mobile phone, he can use the public base station network to make a mobile call within 200m. However, the communication method is generally one-way communication, which can only make outgoing calls and cannot call in. Therefore, it is more convenient to use a wireless pager. For example, if a home base station is installed at the user's place and the local telephone network is connected through the telephone host line, two-way communication can be realized.

Application and billing of cordless telephone service

Users installing cordless phones should go through the registration procedures at the local radio regulatory agency, purchase equipment approved by the Ministry of Posts and Telecommunications to access the network, and be installed by the telephone bureau. They cannot be installed on ordinary telephones. The cordless telephone service is generally charged in a timed manner. Additional charges such as surcharges can also be collected according to local regulations.