The PRX205 is a processor

Stored Program Control exchange

Stored Program Control exchange is the technical name used for telephone exchanges controlled by a computer program stored in the memory of the system. Early exchanges such as Strowger, panel, rotary, and crossbar switches were electromechanical and had no software control...

 controlled reed relay

Reed relay

A reed relay is a type of relay that uses an electromagnet to control one or more reed switches. The contacts are of magnetic material and the electromagnet acts directly on them without requiring an armature to move them...

 telephone exchange

Telephone exchange

In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls...

 developed by Philips

Philips

Koninklijke Philips Electronics N.V. , more commonly known as Philips, is a multinational Dutch electronics company....

 Telecommunicatie Industrie BV (PTI) in Hilversum

Hilversum

is a municipality and a town in the Netherlands, in the province of North Holland. Located in the region called "'t Gooi", it is the largest town in that area. It is surrounded by heathland, woods, meadows, lakes, and smaller villages...

 during the late 1960s and early 1970s. The first public switch was installed in Overvecht in Utrecht

Utrecht (city)

Utrecht city and municipality is the capital and most populous city of the Dutch province of Utrecht. It is located in the eastern corner of the Randstad conurbation, and is the fourth largest city of the Netherlands with a population of 312,634 on 1 Jan 2011.Utrecht's ancient city centre features...

 in 1972. About half of all sales were in the Netherlands. The last PRX switch was taken out of service on 7 December 2010 at Volendam in the Netherlands.

The PRX digital version (PRX/D) was developed during the early 1980s in PTI's laboratories in Hilversum, Brussels

Brussels

Brussels , officially the Brussels Region or Brussels-Capital Region , is the capital of Belgium and the de facto capital of the European Union...

 and Malmesbury, Wiltshire but only went into limited production. PTI first went into partnership with AT&T

AT&T

AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...

 in 1984 and then sold its remaining stake in the company to AT&T (later demerged into Lucent and subsequently merged to form Alcatel-Lucent

Alcatel-Lucent

Alcatel-Lucent is a global telecommunications corporation, headquartered in the 7th arrondissement of Paris, France. It provides telecommunications solutions to service providers, enterprises, and governments around the world, enabling these customers to deliver voice, data, and video services...

) in 1987. After the takeover, the PRX/D development was stopped in favour of the AT&T 5ESS switch

5ESS Switch

The 5ESS Switch is a Class 5 telephone electronic switching system sold by Alcatel-Lucent. This digital central office telephone circuit switching system is used by many telecommunications service providers.-History:...

product, but development of PRX/A continued for some time afterwards. PRX/A systems were installed worldwide including many containerized versions and served reliably for 38 years.