Amber Call-Me-Back

The Amber CMB module enables a new business model whereby subscribers without sufficient funds on their mobile phone account can request another subscriber on the same network to call them back, without having to pay for the notification message. Subscribers access this function via a simple USSD phase 1 call.

Call-Me-Back is an important revenue generator, enabling phone calls between subscribers that otherwise would not have occurred. Subscribers access the CMB module by dialing a USSD short code from their mobile handsets. The basic USSD string includes a short code such as 123 and the MSISDN of the target subscriber. Amber interprets this request and sends an SMS to the target subscriber requesting him or her to call the originator of the request. If the source subscriber registered a name, this name will be included in the SMS message.

The Amber CMB module allows subscribers to dial a USSD short code that prompts them to enter a text string that will be used to identify the subscriber in the CMB SMS message. This text string will be included in the SMS message to the destination MSISDN when the subscriber requests a CMB operation. Amber stores the subscriber details in a highly available realtime database.

In its most basic mode, the CMB Module does not charge subscribers for calls. It is possible to connect the CMB to a charging gateway via a customisation to pre-authorise the Call Me Back operation. It is important to know that in most cases prepaid subscriber will not have any funds available with which to charge for the CMB request. The CMB module tracks the number of requests per MSISDN on a daily basis. This allows the operator to specify the number of free calls to allow before charging the subscriber. If the limit has been exceeded, the CMB module can either reject the request or charge for it via the interface to the charging gateway.

The CMB module generates standard comma delimited call records that includes the following information:

The MSISDN of the requesting subscriber
The MSISDN of the target subscriber
The date and time of the request
A unique reference number

The CMB Module connects to the following network elements:

An SMS-C for sending CMB requests to the target SMS
An SNMP Manager for monitoring statistics and receiving alarms
A USSD gateway such as the Amber USSD Media gateway for receiving USSD requests
The IN Platform for validating that an MSISDN is prepaid (Optional)