MESSAGE CENTER (MC)

MC FUNCTIONS

An MC may be added to a GSM network to provide one or more of the following messaging services:

• Voice mail

• Fax mail

• Short Message Service (SMS) text messages

• SMS Cell Broadcast (SMSCB) text messages

These services can generate considerable revenue for a network operator, as they are becoming increasingly popular.

Voice Mail

Voice mail ensures that all calls to a person can be completed, even when a person does not answer calls. A calling party can record a voice message for the subscriber they are calling. A subscriber can use their MS to select diversion to voice mail based on a particular event or status (e.g. busy, unreachable). The subscriber is informed that they have voice messages in their mailbox by means of either a short text message or phone call from the network at regular intervals. If their MS is detached, this indication is sent when the subscriber next attaches to the network. The subscriber can then retrieve their voice mail messages at a later stage. Functions for storing voice messages over a long period also exist.

Fax Mail

Fax mail operates similarly to voice mail. For MS’s that support fax, a subscriber can set diversion for all or some fax calls to a fax mailbox. When the MS is next attached to the network, the network will deliver the fax message to a fax machine identified by the MS.

SMS

A short text message consists of up 160 alphanumeric characters, entered at a Short Message Entity (SME) such as an MS (using the keypad) or computer terminal. A short message always originates or terminates in a GSM network, meaning that a short message can not be sent between two SMEs residing outside a GSM network. The short message originator knows if the message delivery is successful or unsuccessful via notification. When a message is submitted, the deferred delivery option can be requested. This option makes it possible to specify the time the message is to be delivered. An MC, which handles SMS messages is often referred to as an SMS Center (SMS-C). When a message is to be forwarded to an MS, the system must first determine where the MS is situated. As in ordinary voice traffic, a gateway requests the routing information. The gateway is called the SMS GMSC. Each short message is time stamped by the SMS-Center when it is submitted. A message is deleted once the delivery is successful or once the time specified in deferred delivery expires. When a message is buffered, the SMS-C regularly attempts to deliver the message, at intervals defined by the operator.

SMSCB

The SMSCB service enables a message of up to 93 alphanumeric characters to be delivered to all attached MS’s in one cell. This may be useful for identifying key phone numbers in the cell’s area such as that of a hospital or police station. Alternatively, it may be used for advertising services within the cell (e.g. “Superfood Restaurant in this area at the junction of M8 and I33”).

MC IMPLEMENTATION

One MC node may handle one or more messaging service. For example, depending on the amount of SMS traffic, it may be more efficient to have one MC acting as an SMS-C only, with other messaging services handled by another separate MC. It is also possible to integrate SMS-C functions on an MSC, leading to the term SMS InterWorking MSC (SMS-IWMSC). Additionally, the SMS GMSC functions may reside in the same node as the GMSC functions used for voice calls. In some GSM systems the MC is implemented by MXE product. The most important component of MXE is the message kernel. The message kernel is the central message store and forward nucleus responsible for safe storage of messages, routing and retry attempts.

SMS-C on an MXE