Feature Interaction: An Industrial Perspective

1. Feature Interaction:An Industrial Perspective Greg UtasMay 17 2000

2. Topics • In the next decade, in emerging networks... • Will the number of feature interactions increase or decrease? • Will the interactions become easier or more difficult to resolve? • New services in emerging networks are largely undefined, so... • look at forces that affect new networks, and the characteristics of new networks, to investigate these questions

3. Two definitions • Interaction: a relationship between two features running on behalf of the same user • for example, the flashhook contention between POTS three-way calling and call waiting • important interactions must be specified • Interworking: a relationship between two features running on behalf of different users • for example, call completion to a busy subscriber • must be specified, because they usually involve different systems

4. Standards • More standards => more interactions and interworkings • Forces that create more standards include • differentiation (competition) • interoperability (interworking) • not invented here • creating barriers to entry (protecting incumbents) • levelling the playing field (disrupting incumbents) These forces will increase both the number of interactions and their complexity.

5. Intelligent Network concepts • Service capabilities • don’t specify services, but rather service building blocks • makes interactions more difficult because they cannot be resolved based on the specific services involved • Protocol independence • services need not understand access (UNI) or interworking (NNI) protocols • limits the range of services that can be developed • Application Programming Interfaces (APIs) • AIN, TAPI => JAIN, JTAPI Nothing fundamental has changed.

6. Home Call Server • In existing mobile networks, services run in the call server where the mobile was located when it originated or received its call • service ubiquity; limited differentiation • Next generation mobile networks may separate the signalling and bearer paths • signalling path goes to Home Call Server first, which runs services • bearer path may first go to Serving Call Server, for route optimization or location-based services • Separation of access provider and service provider A Home Call Server increases the degree of interaction and interworking because of differentiation.

7. Intelligent terminals • The power of terminals (“clients”) increases, and so more features will be developed there... • But the network will still be involved: • interworking • proxy (for unreachable terminals) • group services • stimulus signalling • security, performance, or revenue reasons The number of interactions and their complexity increases because of additional terminal-network interactions.

8. Downloadable services • Download services to terminals, SSPs, or SCPs • for example, MExE and WAP for mobile terminals • Will probably be restricted to content-based services • security and quality concerns • complexity issues, at least beyond the IN call model Will probably be limited to services that introduce few interactions.

9. Bearer path architecture • Addition of ATM and IP networks • transcoding and adaptation must be negotiated • broadcasting (e.g. during mobile handover) requires special support • separation of signalling and bearer paths complicates call intercept (wiretap) requirements • multimedia, however, is a simple change to the connection object model Interactions and interworkings become somewhat more complex for connection oriented services.

10. Security and privacy • Often mentioned as issues for IP-based networks, but they even exist today • privacy indicator for calling number • authentication, ciphering, and aliases (TMSIs) in GSM networks • Firewalls in IP-based networks are a new obstacle Security and privacy are new dimensions that increase the complexity of interactions and interworkings.

11. Quality • Increased differentiation => cursory interoperability => reduced quality of interactions and interworkings • Could this persist? • for a while, if users or service providers lower expectations, but... • emerging products want content • established products want schedule • mature products want quality--assuming that maturity is reached Reduced focus on quality => much less focus on interaction. Continued focus on quality => big focus on system integration.

12. Conclusion • More interactions, and more complexity, resulting from • competition, which drives differentation • interoperability, driven by differentiation • services also being developed in terminals • new dimensions of bearer path design, security, and privacy But will reduced quality expectations allow the interaction “problem” to be largely ignored?