Prior art Telephone services which enable a call to be debited to the called party are known; after the call request, if the called party consents to the debiting, the connection is established and the call can take place.

However, at the present time there is only provision for billing the senders of short messages.

Clearly, the problems of billing the recipient of a message are fundamentally different from those of voice calls, and in particular the different nature of the information content and the corresponding transmission protocol require ad hoc solutions which are totally unrelated to the existing procedures for managing voice calls debited to the called party.

The object of the present invention is to enable short messages to be sent with the cost debited to the recipient, this debiting to the recipient being allowed only if the latter has previously authorized the sending number for the operation.

Another object of the present invention is to provide a method for sending short messages with debiting to the recipient which enables both the recipient's number and the data for the type of

billing to the recipient to be sent together with the message.

Finally, another object of the present invention is to provide a method for sending short messages with debiting to the recipient which is based on the typical network architecture of SMS management systems and which uses communication protocols which are standard in the mobile telephony field, in order to make the service inexpensive and immediately usable.

These and other objects which will be made clear in the description are achieved by means of a method comprising the following steps.

1. A user wishing to debit the cost of a short message to the recipient of the message provides the number with a prefix, e. g. consisting of a short number, associated with a platform managing the service. For example, if the recipient's number is 3351234567 and the short number is 4888, the user may dial 48883351234567.

2. When it receives the message, the SMS center SMS- C forwards the same to the platform managing the service, keeping the data relating to the recipient number (prefix+number) unchanged.

3. The platform managing the service checks that the recipient of the message has authorized the sending number to debit the cost of the short message to him.

4. The platform also checks, via a suitable interface with the billing systems, that the recipient has sufficient credit for the operation to take place.

5. If the outcome of both checks is positive, the platform sends the message to the recipient.

6. If the authorization check is negative, a courtesy message may be sent to the sender, informing

him that sending with debiting to the recipient is not possible. The recipient may also be informed of the sender's attempt to debit him, and of the procedures for activating the system.

In order to provide an example of how the service can be implemented, without intent to limit the generality of the invention and its possible fields of application, a specific embodiment of the invention is described below with particular reference to Figure 1 attached.

This figure shows the following message flow: (1) User A sends the SMS with debiting to the recipient, by adding a suitable prefix to the recipient's number.

(2), (3) The SMS-C receives the message, recognizes from the prefix that the SMS message should be debited to the recipient and forwards the same to the software platform SW-P, instead that sending directly to the recipient.

(4) The SW-P platform eliminates the prefix from the recipient's number, in order to recognize the user B to which the message has to be sent, and checks the authorizations set by user B.

(5) The SW-P platform checks the credit of user B.

(6), (7), (8) If user A is not authorized for the debiting or user B has insufficient credit, user A receives the courtesy message.

(9), (10), (11) If user A is authorized for the debiting and user B has sufficient credit, the SW-P platform forwards the short message to the SMS-C, so that it can be sent to user B.

For user B, the fact that he is being billed is transparent because the received message shows the

number of user A as the sender, as for a normal short message.

However, the sent message does not go directly to the recipient but is processed by the dedicated SW-P platform. The forwarding of the messages from the SMS- C and the SW-P platform (and vice-versa) can be carried out by a protocol of the IP suite, such as for example by UCP (Universal Computer Protocol).

Since the system evaluates the incoming message as originating from an application if it is identified by a number, a special arrangement can be made for billing the message: the field of the UCP frame relating to the sender is completed with the sender's number in alphanumeric type. The SMS-C recognizes that the sender field is of the alphanumeric type and generates a traffic record (subsequently sent to the billing systems) showing as sender the recipient's number, instead of the sender's number, and therefore enables the appropriate billing policies to be used.

To encode a string as an alphanumeric OAdC field (the sender of the short message), the following steps may be carried out: 1) The string is encoded in the 7-bit GSM alphabet (for example as shown in table in GSM 03.38 or EMI specifications).

2) The"SMS Point-to-Point Packing"compression algorithm (described in the GSM 03.38 specifications) is applied to the result of the encoding.

3) The number of half-octets produced by the compression algorithm is then placed at the head of the resulting string.

4) The resulting string is finally converted to the alphanumeric representation which the UCP protocol

will use for the messages.

Advantages and possible applications of the invention I-Short message debiting options Three different options are herein disclosed to determine the modes in which a user can authorize other users to debit short messages to his number: 1. Unlimited: a number configured with this option can debit an unlimited number of messages to the recipient.

2. Numeric: a number configured with this option can debit a maximum number N of messages, determined by the recipient. The number N set initially is decremented on the transit of each short message and, when the value reaches zero, the platform sends a courtesy message to the sender, notifying him that short messages cannot be sent with debiting to the recipient.

3. Time-based: a number configured with this option can debit an unlimited number of messages within a time interval specified by the recipient. If the configured number sends a short message with debiting to the recipient outside the entered time interval, it will receive a courtesy message notifying it that the message cannot be resent.

II-Web management interface Easier access for the user can be provided by using the World-Wide Web and corresponding browsers.

A web interface enables the users to manage the lists of numbers authorized for debiting. The allowed operations may be, for example: 1. Display of the list of authorized numbers.

2. Addition of a new number to the list in one of the following modes:

a. Unlimited authorization b. Numeric authorization c. Time-based authorization 2. Activation/Disabling of a number already present on the list.

3. Modification of the entries of numbers present on the list.

4. Removal of a number from the list.

III-Service by Short Message Access via mobile telephone may be also provided.

For example, the users can interact with the platform which manages the service by sending special service SMs containing a special keyword. Most typical operations may include: 1. Entry of a new number authorized for debiting in unlimited, numeric or time-based mode.

A user wishing to authorize a new number for debiting may send a short message showing 4888<number to be activated> as the recipient, and insert the keyword for this option into the message. A further keyword may also be introduced, in order to specify the authorization mode. For example, if a number is inserted into the text in addition to the keyword, the authorization will be of the numeric type; otherwise it will be of the unlimited type. If the number that the user wishes to activate is already authorized, the existing entry may be overwritten with the new request.

2. Removal of a number authorized for debiting from the list.

A user wishing to remove a number authorized for debiting from the list must send a short message showing 4888<number to be disabled as the recipient,

and insert the keyword for this option into the message.

3. Display of the list of numbers The user can receive information on the list of numbers which he has configured, by sending a short message to a service number, such as for example 48883, or, as another example, to the number 4888<own number>, as the recipient, and inserting the keyword for this option into the message.

4. Request for help The user can send a help request message enabling him to receive a courtesy message containing the instructions for using the service by short messages.

Provision may be also made for billing for the various operations associated with the activation, cancellation, status request or the service management in general. For this purpose, each request may be answered with a courtesy message in which the UCP OADC field (sender of the SMS) is set, together with a short number associated with the billing which is to be applied for the specific service message. For this type of message, the sender field is not put in alphanumeric format; instead, the ordinary numeric format can be used (leaving the UCP OTOA field empty).

The keywords, the courtesy messages and the billing short numbers to be used for the service short messages can be determined from a configuration file of the platform.