Patent Application
20070004448
The invention provides a method and apparatus for providing telecommunication backup as well as an exchange system.
Modern life depends to an increasing extent on failure-free and uninterrupted telecommunication. An interrupt in telecommunication services from an entity (e.g. a company, a hospital, an authority, a university, or the like) towards its surrounding may lead to several organizational problems, economical losses or even danger to humans.
A usual setup in an entity, e.g. as mentioned above, is that in the premises of said entity a private branch exchange is installed which exchanges telecommunication between public telephone lines and internal extensions in said premises. The private branch exchange (e.g. a PABX) is used in the customer's premises for handling one or a plurality of public telecommunication lines on the one hand, and a plurality of local extension in the customer's premises, on the other hand. The public telecommunication lines here may be a physical analog telephone line (tip/ring interface) and/or a logical channel, or a plurality of each of them, they may comprise a multi-channel interface, e.g. a T1 trunk, or one or more voice-over-EP interfaces (VoIP).
Many entities protect themselves against a failure of a PABX by using redundant hardware. However, a failure can also occur outside the customer's premises. For example, the public telephone lines may be physically damaged during construction work. Further, the service providers exchange may fail, e.g., due to fire or power outage or natural disasters. Hardware redundancy on the customer's premises does not protect against failures of the latter mentioned kind.
A protection mechanism against physical damage to public telephone lines is to use at least two landline trunks connected to different service providers' exchanges. However, these solutions are typically complex and expensive. Further, point-to-point radio links are known as a backup for a landline failure. Such mechanisms, however, are again expensive and lack flexibility.
It is the object of the invention to provide a method, and an apparatus, and an exchange system for providing telecommunication backup, which are flexible, reliable, and cost-efficient.
This object is accomplished in accordance with the features of the independent claims. Dependent claims are directed on preferred embodiments of the invention.
A method for providing telecommunication backup to one or a plurality of public communication lines providing telecommunication services from or to one or a plurality of extensions comprises the step of managing telecommunication between said extensions and said public communication lines by an exchange. In addition thereto, one or preferably a plurality of wireless channels is provided capable of rendering telecommunication. The exchange routes telecommunication towards said wireless channels, particularly for outbound telecommunication, when some or all of said public communication lines are not available.
The exchange and the public communication lines connected thereto may be chosen and configured such that they are sufficient for ordinary telecommunication under ordinary circumstances, i.e., in the absence of internal and external telecommunication failures. If, vice versa, by such failures telecommunication through the public communication lines is adversely affected (e.g. by making a part or all of the communication lines unavailable because, e.g., a wire was interrupted in the course of construction works outside the premises of an entity), at least a part (e.g. a prioritized part) of the telecommunication may routed through the wireless channels. Such channels are less prone to failure, e.g. cable interruption, fire, flood, and the like.
Wireless channels must be paid for. Often, they come with the offer of pre-paid telecommunication services included e. g. in a basic fee, i.e. an amount of telecommunication that can be used without extra costs. “Prepaid services” in this context may be or include telecommunication services which are periodically, e. g. monthly, offered for no extra costs and which may after a given period, e. g. a month, no longer be available. In these circumstances, the wireless channels actually and primarily provided for backup of public communication lines may also be used under least cost criteria during normal, failure-free conditions in order to consume pre-paid services. Once such pre-paid services are consumed, the routing of ordinary communication through the wireless channels during failure-free conditions may be abandoned or rejected until prepaid services are again available.
The public communication lines may be analog telephone lines or digital lines, particularly logical channels in a multi-channel interface, e.g. a T1 trunk or a voice-over-IP interface (VoIP). The wireless channels may be cell phone communication channels. They may belong to mobile telephony networks, e.g., GSM, CDMA, W-CDMA, and the like.
Managing the wireless channels and the communication through them may be done by a gateway that connects to a usual exchange through a suitable channel, for example one or a plurality of trunks, e.g. a T1 trunk. Then, usual configuration possibilities in the usual exchange are utilized for making the usual exchange properly working with the gateway. The gateway may comprise, among others, an overall control and one or a plurality of interfaces to one or a plurality of wireless channels.
An exchange with usual exchange functions may also be integrated with a gateway to an exchange system. Such an exchange system may have a common control for the usual exchange functions as well as for managing the plurality of wireless channels in view of the applying criteria.
An apparatus according to the invention for providing telecommunication backup for one or a plurality of public communication lines managed by an exchange comprises one or more wireless channel interfaces for wireless telecommunication, one or more interfaces towards the exchange, and messaging means for exchanging control information with the exchange. Said control information exchange comprises sending control information from the apparatus to the exchange for controlling routing of telecommunication from the exchange towards the apparatus.
The apparatus may comprise routing means for routing telecommunication towards one of the wireless channels also in view of least cost criteria, and also in this respect notifying means for exchanging control information with the exchange.
The apparatus may be adapted to or be connectable with a usual, unmodified exchange through a particular interface of said exchange, e.g. a trunk interface, e.g. one or more T1 trunk(s). Thus, the apparatus may be adapted to behave like a T1 trunk towards the exchange. The apparatus may have signaling means for sending control information from the apparatus to the exchange for influencing the operation of the exchange in accordance with the possibilities given there.
With this arrangement a usual exchange may be upgraded by connecting the apparatus to the exchange through one of its interface, particularly an external interface of the exchange, e.g. a T1 trunk interface. The exchange needs not be modified in its hardware setup and may be configured through the usual settings in the exchange to communicate properly with the apparatus.
Said apparatus together with the exchange may form an exchange system, said exchange system being connected to public telecommunication lines, to extension (preferably internal extension) and to wireless channels. In such an exchange system it is also possible to no longer provide the exchange and the apparatus as distinct entities. Rather, they may be commonly constructed having a common control as a joint device rendering the same functions and having the same interfaces.
The above and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention.
In
The public telecommunication lines 2 and the exchange 3 may be dimensioned and configured such that, in everyday life, they are sufficient for providing telecommunication services to and from the extensions 5 in the desired amount and quality of service.
Reference numeral 7 denotes an apparatus for providing telecommunication backup. It backs up—together with its outgoing connections—the telecommunication reaching and leaving the exchange 3 through the public communication lines 2, particularly in the case that these public communication lines 2 are interrupted, reduced, or show poor quality. The apparatus 7 may be a gateway, and communicates with the exchange 3 through one or more lines or channels 6. Between exchange 3 and gateway 7 one or a plurality of T1 trunks may be provided. The gateway 7 is adapted to connect to one or more wireless channels indicated by reference numerals 9 and 10, with a respective network 8 and 11 being behind them. The wireless channels may be from different providers and/or may be of different technical standards. For example, they may comprise GSM, CDMA, and/or W-CDMA. Preferably, a plurality of wireless channels are provided.
One operation mode of the shown system may be as follows: In usual everyday life, the exchange 3 handles the communication between the extensions 5 and the public telecommunication net 1 via lines 2. Upon the occurrence of a failure in the public communication net 1 or in the public communication lines 2 from the public net towards the exchange 3, the failure is detected by, or notified to, the exchange 3, and in response thereto the exchange 3 begins to route outbound calls (originating in one of the terminals or extensions 5) through the lines 6 towards gateway 7, from where they are further routed through the wireless channels according to predetermined criteria. Thereby outbound communication may be upheld to a given degree through the channels 9 and 10, even if the communication through the public communication lines 2 is disturbed or interrupted.
The general operation of the control 21 is that it receives call setup requests through one of the interfaces 22 connecting to the exchange 3, and decides whether to accept or reject such a setup. If a setup is accepted, the control unit decides which wireless channel and, accordingly, which interface is to be used, sends a call setup to the respective interface and interconnects the respective interface with the respective channel from the exchange. In accordance therewith, a call detail record may be generated and stored. Telecommunication thus routed may be logged. If a setup request is rejected for routing for some reasons, this will be communicated to the exchange 3 so that the request will further be handled in the exchange 3. Together with the rejection, the apparatus 7 may send rejection information to the exchange 3 for informing the exchange 3 about the reason of the rejection. For different reasons of rejections, different rejection information may be sent back to the exchange.
The provision of the wireless channels 9 and 10 is a service that must be bought by the customer. In many cases, this is connected with a certain amount of pre-paid telecommunication services. This has the consequence that through the provision of backup capacity by the gateway 7 the user thereof owns free telecommunication services according to the tariffs applying for the various wireless channels 9 and 10. One feature of the gateway 7 is that it routes outbound telecommunication through one or more of the wireless channels according to least cost criteria. For this, a least-cost-router 24d is provided. It will have the effect of using up free communication services assigned to the back-up wireless channels. Thereafter, the least-cost-router will reject call requests from the extension, unless it is forced to accept them or unless it has free services again. This may involve one or more of the following features:
Routing outbound telecommunication through one of the wireless channels 9, 10 by routing control means 24f in accordance with the kept records and comparison results.
Issuing control information through notifying means 24g towards the exchange 3 in order to influence and control the routing of outbound telecommunication from extensions towards gateway 7. This may particularly comprise prompting the exchange to route outbound telecommunication to the gateway 7 as long as free communication services are there, even if no failure in the ordinary telecommunication system (public communication lines 2, public net 1) is present. If the prepaid services are consumed, it may involve interrupting routing of call requests from the exchange 3 to the gateway 7 or rejecting such call requests. Likewise, the notifying means 24g may receive control information from the exchange 3.
Distinguishing whether a call request from the exchange is one in view of least cost criteria (a “voluntary wireless routing”) that may be rejected or a necessary wireless routing that must be accepted because of trouble in the usual telecommunication system.
Error detection in the usual telecommunication environment (i.e. in
The apparatus 7 and, particularly, the control 21 thereof may comprise one or more priority means 24b for routing communication originating from a predetermined extension or from a group of predetermined extensions to a particular wireless channel while communication originating from other extensions is not routed to said particular wireless channel. This gives some kind of priority to those extensions assigned to said particular wireless channel, because said channel is kept free for only those extensions assigned to it. For example, one such priority means may allocate the extensions of important executives and managers of a company to one wireless channel. A second priority means may be assigned to particular extensions of the IT department for being able to quickly fix problems by external communication. If a plurality of priority means is provided, they may have a priority order amongst each other, this leading to the highest priority communications being always being connected whenever there is a wireless channel available, the next-lower priority communications always being connected when a wireless channel except that reserved for the highest priority is available, and so on.
The gateway 7 and, particularly, the control 21 thereof, may comprise a suppressing means 24a for suppressing the calling line identification (CLI). This suppressing means suppresses—or replaces—the calling line identification attached to a outbound communication request via the wireless channel. By default, the CLI of a wireless channel is not the number of the calling party, but rather the number under which the wireless channel may be reached. If this wireless channel number is sent as CLI, it may provide wrong information to the called party. Therefore, the suppressing means 24a may suppress such a technically correct, but logically wrong CLI. As far as possible, it may replace this CLI by another value, e.g., by the number of the calling party. Further, the suppression means 24a may keep a table for those extensions which require their extension being shown correctly to the called party. The suppression means will then also comprise the feature that calls voluntarily routed through the gateway 7 and mobile channels (i.e. under least cost routines, not under emergency backup routines) are rejected from being routed through the wireless channels. Rather, the call will go back to the exchange and will be routed from there through conventional channels with correct CLI being shown.
The gateway 7 may reserve one or more wireless channels exclusively for incoming calls and may keep them free from outbound calls and communication. In this respect, it may also comprise changing means 24c for changing the wireless channel reserved for inbound traffic such that once in a while a channel reserved for inbound traffic is used for outbound traffic, and vice versa. The reason therefor is that, if free telecommunication services are allocated to an channel 3 used only for inbound communication, these services might not be consumed by inbound traffic only. Therefore, in order to consume free telecommunication services by outbound communication, channels reserved for inbound communication are changed from time to time or under predetermined criteria.
The apparatus 7 may comprise an identifying means 24h for identifying particular outbound call requests from the exchange 3. Such calls are not rejected by the gateway 7 from routing via one of the wireless channels (except, of course, all channels are occupied or perhaps kept free for priority reasons). However, rejections under other criteria (e.g. free telecommunication services being used up, CLI must be displayed properly) will no longer be made. Such an identification may be used when the usual telecommunication structure is disturbed. A particular identification may then be added to the outbound calls routed from the exchange to the gateway 7. The gateway 7 recognizes from the attached information, e.g. a dialing prefix, that such requests must not be rejected, unless they can technically be routed. But as already said, the priority means 24b may be more powerful than the forced routing accomplished through a particular information recognized by the identification means 24h.
The above mentioned differing rejection information for different reasons of rejections of call requests by the gateway 7 may comprise so-called “cause values” CVn for at least one or more of the following situations:
CV1: . . .
CV2: No mobile net available
CV3: No SIM or SIM error
CV4: No channel available in external net
CV5: No channel (with suitable priority) available in the gateway
CV6: CLI must be shown properly
CV7: No free services available
CV8: . . .
The exchange 3 may be configured to evaluate the rejection information and to take appropriate subsequent action, e. g. routing a call through the public communication lines 2. Under some rejection information, an alarm may be generated, service may be requested or the like. The gateway 7 sends such information to the exchange 3 through messaging means 24i.
Further, the gateway 7, and particularly the control 21 thereof, may comprise an inbound routing means 24j. It may be configured such that it routes through the exchange particular wireless channels to particular extensions. This can be accomplished by examining the number of the called wireless terminals, and particularly looking whether an extension on the user's premises is allocated to said wireless channel. If yes, the incoming call is routed to said extension. Then, such an allocated wireless channel behaves just like a cell phone owned by the person to which the routed extension belongs. In this case, if outgoing calls are routed through such a wireless channel with incoming extension allocation, the CLI may be suppressed in response to the allocation of the incoming calls to an extension.
The decisions and interrogations described so far in
If, however, the gateway 7 is forced to accept the call request (by a particular information attached to the call request, e.g., a prefix, checked in step 302), the priority status of the calling party is checked in step 309. If it is class 1 priority, it is checked in step 310 whether a mobile channel with class 1 priority or lower is available. If yes, the requested call is set up. If no, the requested call must be rejected, because no channels are available. If in step 309 the decision is that the calling party does not enjoy class 1 priority, it is next decided in step 313 whether a class 2 priority is given. If yes, it is checked in step 314 whether an outbound mobile channel with said priority class 2 or lower is available. Again, if yes, the requested call is set up in step 315. If no channel with priority 2 or lower is available, the call request must be rejected due to unavailability of suitable channels. If, in step 313, it is decided that the calling party does not enjoy priority class 2, the priority interrogation is continued in the same way as described so far. Finally, for a not at all prioritized calling party the gateway will check as to the availability of a normal wireless channel and will set up the call if such a normal is channel is available. And if it is not available, again the call request must be rejected.
Alternatively, calls not being mapped on a particular extension calls may be routed through the exchange to a switchboard or operator for further routing there.
Further, one of the provided wireless channels may have an external priority with prioritized access to the network facilities and network channels. This will be useful, particularly in disaster scenarios where telephone networks are usually overloaded. In such situations, a wireless priority service (WPS) has external prioritized access over usual subscriptions. Internally, such a channel may be treated according to one of the above mentioned options.
While the present invention has been illustrated by a description of various embodiments and while these embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method, and illustrative example shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant's general inventive concept.
