CAMEL: Intelligent Networks for the GSM, GPRS and UMTS Network
Rogier Noldusprotocol. The INAP was mainly used in the fixed network environment and it worked well. However,
the main issue was that the INAP deployments were vendor- and operator-specific since the INAP
specification was lacking in some details. For example, many parameters are octet strings – leaving
it up to the vendor to specify the precise encoding.
The other key functionality missing from INAP was mobility. The GSM system was becoming
the dominant mobile network, and allowed for mobility between countries. The mobile operators
were now seeing a real need to provide services to their subscribers when they were roaming.
To address these needs, ETSI started a project called CAMEL in late 1995. First, someone
invented a distinctive name and then the words were filled in later. In fact, very few people
actually remember what the ‘abbreviation’ actually stands for, including myself. As a result of this
activity, CAMEL phase 1 was developed. CAMEL phase 1 is a very simple standard, but is tailored
to the GSM-based core networks. One could claim that CAMEL is a child of INAP.
The CAMEL phase 2 extended CAMEL phase 1, the main focus being prepaid services. Then
CAMEL and other GSM/UMTS works were moved to 3GPP responsibility, as the development of
the 3G network was starting to become a global exercise. CAMEL phase 3 expands the service
to include Short Message Service (SMS) as well as GPRS. Leading the pack, CAMEL phase 4 is
the most advanced of the phases. It has about the same level of functionality as the Core INAP
CS2 for fixed networks. The CAMEL phase 4 is the last CAMEL phase but it is extensible for
any enhancements. In particular, the CAMEL phase 4 Call Party Handling has raised much interest
among operators.
The original scope of CAMEL was the mobility but CAMEL has also been deployed for intra-
network use in multi-vendor cases. Its deployment has begun in the large countries,
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