The present invention relates to a method for transmission of alarm signals, and is based on utilization of an entrance telephone set syste connected to a public automatic subscriber telephone network of the typ disclosed in Swedish Patent No. 373474.

It is previously known to utilize a public subscriber telephone network for transmission of various types of alarm signals, either utilizing coπtinously switched-through connections, or utilizing mechanically or electronically operated automatic dialling equipment, during alarm condition arranged to facilitate connection via a telephone line to a predetermined subscriber telephone number, e.g. an alarm surveillance centre.

Swedish Patent No. 373474 discloses how a public telephone network can be used for entrance signalling and door opening purposes. By means of telephone line from a building, specific entrance calls are switched vi the public telephone network to tenants within the building. This is made possible by the use of a device, referred to as "the Number Discriminator", restricting the use to preprogrammed, but otherwize conventional telephone numbers. A common "automatic dialler", which can only dial one or a number of certain preprogrammed telephone numbers, acts as such a discriminator, since calls can only be made to parties dialled by the automatic dialler. However, this is only true, provided that no other conventional methods for dialling are offered to the calling party. A device as indicated above could be denominated as an "active" number discriminator, which by design and programming has been preset with regard to which telephone number to be dialled, based on th way in which the device is addressed. The telephone number dialler is thus only accessable for a visitor by means of a conventional name/ signalling panel. When the signalling key for a certain tenant is depressed, or by short number or telephone subscriber number selection from a key set, an "entrance call" is initiated.

The object of the present invention is to disclose how an installation of the above described type also can be utilized for an additional purpose, i.e. transmission of various types of alarm signals, while

maintaining previously intended functions.

The previously mentioned number dialler can also be addressed from other locations, and thereby cause connection of other categories of calls. This feature is used according to the present invention in conjunction with an entrance telephone set installation of the type disclosed in the aforementioned Swedish Patent No. 373474 for accomplishing transmission of various types of alarm signals.

The method according to the present invention is thus based on the existence of a entrance telephone set installation of above stated type, connected to a public telephone subscriber network and including a selectively addressable telephone number dialling device, and is mainly characterised in that said telephone number dialling device is connected to one or a number of manually or automatically operable alarm indicators, which when operated initiate diall ng of predetermined telephone numbers.

A basic embodiment of an installation of the above described type will now be mqre fully described with reference to the accompanying drawing.

Said drawing shows a sche atical block diagram, which basically corresponds to the block diagram forming a part of previously mentioned Swedish patent. Since included parts are substantially previously known and described in said publication, such previously known parts will not be discussed. However, the block diagram also shows a number of alarm indicators, denominated 1, 1 ^' , and 1". Said alarm indicators are connected to the number discriminator, either directly, or via incoming signal indicating means. The alarm indicators are advantageously arranged having priority, thereby, during alarm conditions, interrupting existing connections, or attempts to establish connection, between the entrance telephone set and subscribers connected to the installation.

As an example, a manually operable alarm indicator could for instance comprise of a pushbutton marked "EMERGENCY" and associated unit for verbal communication. This would offer the possibility of making an emergency call to an emergency alarm centre, If, and where, such a pushbutton should be available, would be a policy question.

OM WIP *NA

A technically and economically more important advantage is related to a different field of use. Most buildings requiring an entrance telephone installation, normally also require alarm installations. By reductions made in the number of employees, such as caretakers, more buildings are now made "unmanned". Lift alarm systems, boiler fault alarm, fire and burglary alarm systems, constitute examples of alarms which require attention, and alarm installations transmitting various types of alarms via the public telephone network to certain recipients, e.g. alarm surveillance centres and security companies, are coming more and more into demand. Presently used types of such installations require access to an outgoing telephone line connected to a telephone exchange, and also some type of automatic dialling equipment, which automatically dials the intended subscriber telephone number, based on which sensing device that has been activated to address same.

A building having an entrance telephone set installation of the type disclosed in the aforementioned Swedish Patent No. 373474 has access to an outgoing telephone line and an automatic telephone number dialling device. By a small addition to such an installation, basically only to the cost of discussed various types of sensing devices, such a building receives the ability to transmit alarm signals via the public telephone network. The number of various alarm types can be decided on basis of actual demand, and also on basis of type/location/number of different sensing devices, which are arranged to address the number discriminator to dial and make specific calls/alarms for each sensing device that is influenced.

Certain types of alarms are more suitable than other. As a rule, alarms common for a building, such as for example lift, boiler, burglary and fire alarms, are preferably sent via the outgoing telephone line common for the building, whereas more specific alarms for each tenant, such as e.g. flat burglary alarms, old age people and safety surveillance alarms and similar, are as previously more suited to be transmitted via the various tenants private outgoing telephone lines.

A major advantage is, that lift alarms via the public telephone network makes it possible to establish verbal contact with persons trapped in a lift, and thus possibility to give such persons reassuring information.