intelligent network The Intelligent Network (IN) is the standard network architecture specified in the ITU-T Q.1200 series recommendations. It is intended for fixed as well as Global System for Mobile Communications, mobile telecommunication, telecom networks. It al ...

s (IN) and cellular networks, service layer is a conceptual layer within a network service provider architecture. It aims at providing middleware that serves third-party value-added services and applications at a higher

application layer An application layer is an abstraction layer that specifies the shared communications protocols and Interface (computing), interface methods used by Host (network), hosts in a communications network. An ''application layer'' abstraction is speci ...

. The service layer provides ''capability servers'' owned by a telecommunication network service provider, accessed through open and secure

Application Programming Interface An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how t ...

s (APIs) by application layer servers owned by third-party content providers. The service layer also provides an interface to core networks at a lower resource layer. The lower layers may also be named control layer and transport layer (the transport layer is also referred to as the access layer in some architectures). The concept of service layer is used in contexts such as

Intelligent network The Intelligent Network (IN) is the standard network architecture specified in the ITU-T Q.1200 series recommendations. It is intended for fixed as well as Global System for Mobile Communications, mobile telecommunication, telecom networks. It al ...

s (IN), WAP, 3G and

IP Multimedia Subsystem The IP Multimedia Subsystem or IP Multimedia Core Network Subsystem (IMS) is a standardised architectural framework for delivering IP multimedia services. Historically, mobile phones have provided voice call services over a circuit-switched-styl ...

(IMS). It is defined in the 3GPP

Open Services Architecture The Open Service Access or OSA is part of the third generation mobile telecommunications network or UMTS. OSA describes how services are designed in a UMTS network. The standards for OSA are being developed as part of the 3rd Generation Partnership ...

(OSA) model, which reused the idea of the

Parlay A parlay, accumulator (or acca), combo bet or multi is a single bet that links together two or more individual wagers and is dependent on all of those wagers winning together. The benefit of the parlay is that there are much higher pay-offs th ...

API for third-party servers. In software design, for example Service-oriented architecture, the concept of service layer has a different meaning.

Service layer in IMS

The service layer of an

IMS Ims is a Norwegian surname. Notable people with the surname include: * Gry Tofte Ims (born 1986), Norwegian footballer * Rolf Anker Ims (born 1958), Norwegian ecologist See also * IMS (disambiguation) Ims is a Norwegian surname. Notable people wit ...

architecture provides multimedia services to the overall IMS network. This layer contains network elements which connect to the Serving-CSCF (Call Session Control Function) using the IP multimedia Subsystem Service Control Interface (ISC). The ISC interface uses the SIP signalling protocol.

Elements of the IMS service layer

The network elements contained within the service layer are generically referred to as 'service platforms' however the 3GPP specification (3GPP TS 23.228 V8.7.0) defines several types of service platforms: * SIP Application Server * OSA Service Capability Server * IM-SSF

SIP Application Server

The SIP Application Server (AS) performs the same function as a Telephony Application Server in a pre-IMS network, however it is specifically tailored to support the SIP signalling protocol for use in an IMS network.

OSA Service Capability Server

An OSA Service Capability Server acts as a secure gateway between the IMS network and an application which runs upon the

(this is typically a SIP to

gateway)

IM-SSF

The IM-SSF (IP Multimedia Service Switching Function) acts as a gateway between the IMS network and application servers using other telecommunication signalling standards such as INAP and

CAMEL A camel (from: la, camelus and grc-gre, κάμηλος (''kamēlos'') from Hebrew or Phoenician: גָמָל ''gāmāl''.) is an even-toed ungulate in the genus ''Camelus'' that bears distinctive fatty deposits known as "humps" on its back. C ...

Service layer in SOA

In service-oriented architecture (SOA), the service layer is the third layer in a five-abstraction-layer model. The model consists of Object layer, Component layer, Service layer, Process layer and Enterprise layer.Service-oriented Architecture Compass: Business Value, Planning, and Enterprise Roadmap. Author: Norbert Bieberstein, Sanjay Bose, Marc Fiammante, Keith Jones, Rawn Shah. Edition: illustrated. Published by: FT Press, 2005.
The service layer can be considered as a bridge between the higher and lower layers, and is characterized by a number of services that are carrying out individual business functions.

References

{{Reflist Application layer protocols Service-oriented (business computing) Middleware