{"id":2936,"date":"2023-08-03T12:18:31","date_gmt":"2023-08-03T12:18:31","guid":{"rendered":"https:\/\/www.avire-global.com\/articles\/?p=2936"},"modified":"2023-09-13T07:41:12","modified_gmt":"2023-09-13T07:41:12","slug":"analogue-to-fibre-the-urgency-for-gsm-in-the-lift-industry","status":"publish","type":"post","link":"https:\/\/www.avire-global.com\/articles\/analogue-to-fibre-the-urgency-for-gsm-in-the-lift-industry\/","title":{"rendered":"Analogue to fibre: the urgency for GSM in the lift industry"},"content":{"rendered":"\n
Lift phone regulations require that emergency communication always be available for passengers. Traditionally this is met via fixed landlines, however as telecoms networks move to fibre, support for analogue signalling (including DTMF) is decreasing.<\/p>\n\n\n\n
The transition of analogue telephone lines is seeing the permanent removal of copper lines which are being replaced and transitioned to digital fixed lines or modems. Though fibre is a faster and more efficient technology for telephone transmission, it cannot be always relied upon when using legacy lift equipment.<\/p>\n\n\n\n
Introduced in 1963 \u2018Dual Tone Multi Frequency\u2019 (DTMF) signalling has been a mainstay of telecommunications networks all over the world. Often referred to by the original Bell System commercial name \u2018touch tone\u2019, every time you \u201cPush 1 for Sales\u2026\u201d on a telephone keypad you are using DTMF signalling.<\/p>\n\n\n\n
Most lift emergency telephones installed today, use DTMF signalling to transfer operator signals (playing location messages, muting in car microphones etc.) and, in the case of telephones conforming to EN81-28, transfer test information as part of the 3-day test call procedure.<\/p>\n\n\n\n
DTMF signally is an analogue signalling system which consists of 16 audible tones generated by the 0-9, \u2018#\u2019, and \u2018*\u2019 keys on a standard telephone keypad and A, B, C, D keys typically only found on telephone engineer testing equipment.<\/p>\n\n\n\n
DTMF tones are transmitted, over the voice channel of the telephone network, between two devices to transfer information. Using the example above, pressing the \u20181\u2019 key generates a specific tone telling the automated switchboard that you want to be connected to the sales department.<\/p>\n\n\n\n
In addition to the consumer telecoms application, DTMF is used in machine to machine (M2M) communication. A device generates a stream of DTMF tones to transfer information over the telephone network to a receiver which then decodes the tones into readable data. It\u2019s this M2M application that includes the elevator industries operator instructions and 3-day test call information.<\/p>\n\n\n\n
Any disruption to the sequence of the tones, or distortion to the tones themselves, will result in the information being unintelligible at the receiving end. Because DTMF tones are an analogue audio signal, any interference on the voice channel will distort the tones.<\/p>\n\n\n\n
As new technologies have emerged, analogue signalling has become less and less popular as a means of transferring data. In turn telecoms networks have begun to provide less support for these legacy signalling types, including DTMF.<\/p>\n\n\n\n
At a national level, Public Switch Telephone Networks (PSTN, aka \u201clandlines\u201d) across the globe have begun to set dates, typically 2025 onwards, for the end of DTMF support on their networks. This is in conjunction with the rollout of fibre optic telephone lines more suited to carrying data. At that point emergency telephones trying to place three-day background calls over the PSTN, will be unable to communicate using DTMF and therefore will not be able to confirm they are in working order (resulting in \u201cfailed\u201d test calls).<\/p>\n\n\n\n
When mobile networks were introduced in the 1990s support for DTMF was carried over from the PSTN. However Mobile Network Operators (MNO) use compression technology to transfer tones through the voice channel. This compression can then result in the tones being distorted either by affecting the timing of the tones or \u201cclipping\u201d the upper or lower frequencies. Each generation of mobile technology from 2G onwards has provided less and less support for the high quality DTMF needed for M2M communication.<\/p>\n\n\n\n
Fibre broadband and other fibre services such as FTTP (fibre to the premises) use optical fibre. These thin fibres can be delivered straight to premises and deliver almost unlimited speed. They efficiently deliver data at very high speeds and require significantly less space than copper lines (being only a fraction of the size of copper lines).<\/p>\n\n\n\n
As a result, fewer copper landlines are currently being installed. Delays and waiting times for these are increasing and maintenance of the already existing lines is consistently decreasing.<\/p>\n\n\n\n
To support this switch to fibre, some companies increase the cost of copper installation making it less attractive. The increase of cost has already been seen in other countries such as Australia, where NBN has led the removal of a predominantly copper network, to rollout their Multi Technology Mix (MTM) leading to the complete removal of their copper network.<\/p>\n\n\n\n
Due to the European standard EN81-28<\/a>, emergency lift telephones are required to, at a minimum, carry out three-day background calls to confirm they are working and performing to correct specifications. Later generation devices can perform these checks through the data network, however analogue devices cannot without assisted technology. Instead, they make use of analogue DTMF signals to comply with the requirements.<\/p>\n\n\n\n Traditional copper landlines are capable of analogue transmission only, which made them the traditional method of choice. The newer, fibre optic lines are capable of analogue simulations, and could, in theory, be installed instead of copper lines. However, communication providers are removing the analogue simulation, thus making it incapable of carrying DTMF tones for background calls.<\/p>\n\n\n\n This change means fibre lines now make the use of legacy equipment void. When this happened in Australia, where the new NBN network was incapable of analogue transmission from the beginning, it led to many compatibility issues.<\/p>\n\n\n\nHow to ensure lift emergency phone resilience?<\/h2>\n\n\n\n