Final answer:
The question primarily deals with the historical and current use of telephone lines, the impact of mobile cellular subscriptions, the presence of secure Internet servers, and electricity production as indicators of technological and economic development in society.
Step-by-step explanation:
The number of telephone lines in use is a metric that reflects the telecommunications infrastructure of a society or country. Over time, the reliance on traditional landline telephones has diminished due to the rise of mobile cellular subscriptions and the increased personalization of communication technologies. Secure Internet servers per one million people and electricity production in kWh are additional measures that indicate technological advancement and energy consumption patterns within a region. These metrics play a vital role in understanding socio-economic development and can inform policy decisions related to technology, energy, and communication sectors.
The history of the telephone itself is substantial, with its invention in 1876 sparking a communication revolution and leading to over 1.5 million telephones in use by 1900. Today, the usage has expanded to include various services such as caller id, voicemail, and privacy managers, which address the changing nature of personal schedules and societal norms around privacy and communication.