Description
The Forwarded-To NetWork (FTNW) is a network-level identifier parameter used within advanced call forwarding and routing scenarios in GSM/UMTS networks. Unlike the FTN, which specifies a destination telephone number, the FTNW specifies the Public Land Mobile Network (PLMN) or another network domain to which a call should be routed. This parameter is particularly relevant in the context of Camel (Customised Applications for Mobile network Enhanced Logic) services and Optimal Routing (OR) procedures, where call path optimization and service control across network boundaries are required.
Architecturally, the FTNW is stored alongside or in conjunction with forwarding data in the HLR. When a call forwarding condition is invoked and the forwarding target is determined to be in a different network, the FTNW can be provided to the Gateway MSC (GMSC) or other routing nodes. This informs the routing logic that the call should be directed towards a specific network identifier (e.g., a Mobile Country Code and Mobile Network Code - MCC/MNC combination) for further processing. The GMSC can use this information to select an appropriate breakout trunk or signaling route towards that network.
In Camel scenarios, the FTNW plays a role in the dialogue between the gsmSCF (Camel service control function) and the GMSC or MSC. When a Camel service influences call forwarding, the gsmSCF may provide an FTNW as part of its instructions, guiding the call to a network where further service logic (like a prepaid platform or intelligent peripheral) resides. This allows for the seamless extension of services across multiple operator networks and supports complex, value-added call flows that depend on network-aware routing decisions.
Purpose & Motivation
The FTNW was introduced to address the limitations of simple number-based forwarding in a multi-operator and intelligent network environment. As networks evolved with Camel and a focus on optimal routing, merely having a destination number (FTN) was insufficient for efficient call setup. The network needed to know *which* network to send the call to first, especially for toll bypass, least-cost routing, or triggering network-specific service platforms.
Its creation in Release 4 was motivated by the need for more granular control over inter-PLMN call routing. It solved the problem of suboptimal call paths where a call might be routed back through the home network unnecessarily, increasing cost and latency. By specifying the FTNW, the home network could instruct the GMSC to route the call directly towards the network where the forwarded subscriber was currently located or where a service node existed, enabling Optimal Routing. This was a key enabler for cost-effective international roaming and advanced, network-hosted telephony services that required precise control over the call path across administrative boundaries.
Key Features
- Identifies a destination network (PLMN) rather than a subscriber number
- Used in conjunction with Camel service logic and Optimal Routing procedures
- Informs GMSC routing decisions for inter-network call forwarding
- Supports efficient toll bypass and least-cost routing scenarios
- Parameter exchanged via MAP signaling between HLR and GMSC/MSC
- Enables network-aware service triggering for advanced telephony services
Evolution Across Releases
Introduced as a new parameter to support network-aware call forwarding, primarily for Optimal Routing and Camel-based services. Defined its encoding as a network identifier and its inclusion in relevant MAP operations to guide the GMSC in selecting the appropriate onward routing path towards a specific PLMN.
Defining Specifications
| Specification | Title |
|---|---|
| TS 23.018 | 3GPP TS 23.018 |
| TS 23.079 | 3GPP TS 23.079 |