Page 47 - ITU-T Focus Group Digital Financial Services – Consumer Experience and Protection

ITU-T Focus Group Digital Financial Services
Consumer Experience and Protection

To do this, the SMSC sends a SMS Request to the home location register (HLR) to find the roaming customer.
Once the HLR receives the request, it will respond to the SMSC with the subscriber's status: 1) inactive or
active 2) where subscriber is roaming.
If the response is "inactive", then the SMSC will hold onto the message for a period of time. When the
subscriber accesses his device, the HLR sends a SMS Notification to the SMSC, and the SMSC will attempt
delivery.

The SMSC transfers the message in a Short Message Delivery Point to Point format to the serving system. The
system pages the device, and if it responds, the message gets delivered.
The SMSC receives verification that the message was received by the end user, then categorizes the message
as "sent" and will not attempt to send again.

SMS falls into the group of the so-called store-and-forward services and is normally being transported in the
background class according to 3GPP TS 23107. As a consequence, parameters like SMS delivery time or SMS
response time depend very much on the traffic load of the mobile network and cannot be guaranteed.

B.1.2 Interactive Voice Response (IVR)
Interactive voice response (IVR) is a technology that allows a computer to interact with human users through
the use of voice and DTMF tones input via keypad.

In telecommunications, IVR allows customers to interact with a company’s host system via a telephone keypad
or by speech recognition, after which they can service their own inquiries by following the IVR dialogue. IVR
systems can respond with pre-recorded or dynamically generated audio to further direct users on how to
proceed. IVR applications can be used to control almost any function where the interface can be broken down
into a series of simple interactions.

B.1.3 Dual Tone Multi Frequency (DTMF) signalling

The DTMF system uses a set of eight audio frequencies transmitted in pairs to represent 16 signals, represented
by the ten digits, the letters A to D, and the symbols # and * as described in Recommendation ITU-T Q.23.
Detailed requirements for DTMF are specified in ETSI ES 201 235. As the signals are audible tones in the voice
frequency range, they can be transmitted like speech signals. Originally used to dial the number of the remote
terminal, it became a common method to transmit small amounts of data.

In packet based networks there are 3 common ways of sending DTMF:

• SIP INFO packets as described in IETF RFC 2976
• As specially marked events in the RTP stream – as described in IETF RFC 2833
• Inband as normal audio tones in the RTP stream with no special coding or markers

For mobile networks 3GPP TS23014 describes how DTMF signals are supported. A message based signalling
system is used across the 3GPP system air interface. Inband transmission is not possible. That means that in
mobile communication the originating mobile terminal is directly creating the relevant messages when the
keys are pressed by the user during a call.

B.1.4 Unstructured Supplementary Service Data (USSD) – both push and pull services

Unstructured Supplementary Service Data (USSD) is a protocol used by mobile terminals to communicate with
the network of the mobile operator.

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