Today in 1958, Queen Elizabeth II inaugurated Subscriber Trunk Dialling (STD) in the UK by when she spoke to the Lord Provost in a call from Bristol to Edinburgh.  In the first half of the 20th century, telecommunication services developed progressively from completely manual setup of calls by operators, who were called by subscribers, to automatic systems that could connect subscribers of the same local exchange through the use of telephone dials installed in each telephone - STD.  

Since the late nineteenth century phone calls in the UK have been handled by the public switched telephone network (PSTN). This is the umbrella term for the complex infrastructure of telephone lines, satellite links, and switching centres which connect one caller to another when a specific phone number is entered.  Internet calls, video conferencing and online collaborative tools have far exceeded the capabilities of PSTN and it is becoming increasingly difficult to maintain.  By the end of 2025, PSTN will be switched off across the UK, ushering in a new era of telecoms.  Digital services will take its place, namely internet protocol (IP) or voice over internet protocol (VoIP) phone systems through which business users can make calls via broadband or mobile data.  To understand the implications of this, talk to Joe Concheiro.