The Role of CAMEL

CAMEL has been specified to allow operator-specific services (IN services) to be
provided for subscribers even while roaming abroad. The service control point
(SCP) is generally located in the home network, allowing serving network switches
to interact with it to provide the advanced services.
CAMEL is an acronym for Customized Applications for Mobile networks
Enhanced Logic, and has been specified to allow for the introduction of IN
services in mobile networks alongside both call control functions and mobility
management.
In the later phases of CAMEL, it also allows for the provision of advanced
services in support of GPRS, SMS, and supplementary services. The interfaces
required for CAMEL are standardized to a high degree, allowing network elements
from different networks to work together using the CAMEL Application
Part (CAP) message set of Signaling System Number 7 (SS7). An example CAMEL
procedure is shown in Figure 3.47 for clarity.
The aim is to allow Intelligent Network interactions with a service control point
located in the subscriber’s home network. CAMEL takes account of mobile originated,
mobile terminated, and mobile forwarding cases, and also allows for both
roaming and non-roaming cases.
Modifications at the MSC essentially give the switch the ability to recognize the
requirement for a CAMEL-based service and build the required messages for the
specified SCF. In addition, both the HLR and VLR must be modified to hold the
relevant CAMEL subscriber details.
CAMEL has been defined in different phases to allow a staged approach to
implementation. Each phase is a superset of the previous one. Not all networks will
be at the latest phase of CAMEL, or even support CAMEL at all — but in many
networks, CAMEL is used to support prepaid services.