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Kamailio sca

Kamailio sca



Brief overview of the Shared Call Appearances module in Kamailio

Brief overview of the Shared Call Appearances module in Kamailio



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    Kamailio sca Kamailio sca Presentation Transcript

    • Shared Call Appearances in Kamailio Andrew Mortensen University of Pennsylvania
    • PennNet Phone • Started as part of the sip.edu initiative • Ran SER 0.9.x for several years • Gained traction due to cost savings, now nearing conclusion of migration to entirely VoIP deployment • 14K VoIP handsets now, targeting 18K • Roughly 100K calls per day, spikes considerably higher • Uncomplicated architecture for now • Replicated proxies and registrars, Asterisk, SEMS
    • PennNet Phone Migration: Requirements • Usual suspects • Voicemail, transfers, forwarding, etc. • Bridged Line Appearances
    • Bridged Line Appearances • Event package using XML bodies to deliver line state to subscribers • Fine for small groups • Local patches to the existing got us BLA in deployment • But…
    • Bridged Line Appearances: Limitations • XML bodies quickly increased NOTIFY packet size • Fragmentation, retransmission • Fragmentation of almost every packet, considerably worse for large BLA groups • Underpowered handsets quickly overwhelmed by fragmented packets • Stuck states
    • Bridged Line Appearances: Alternatives • Shared Call Appearances • …in Kamailio!
    • What is SCA? • Broadsoft spec for shared line events • • Widely implemented by handset vendors SCA group receives notifications when a member does something interesting • line seize, ringing, answered, held • Held calls can be retrieved by any other member of the group • Line state delivered in compact Call-Info headers!
    • SCA at Penn • Agreement that BLA was a dead end • In-house familiarity with SER/Kamailio code • 3-4 months of development • • RFC 3891 support (“Replaces” header) to retrieve held calls Rapid rollout following successful testing
    • SCA at Penn: Results? • Largest supported group size • BLA: 6 • SCA: 24 (imposed by handset limitations) • 8000+ handsets using SCA, many with multiple SCA lines • Stuck states? Almost eliminated.
    • SCA at Penn: Results? • Opens possibility of using other vendor handsets • • • Tested with Polycom, Aastra, Cisco, Yealink Likely to work with Snom, Grandstream, others BYOD?
    • Simple Demo
    • Future Directions • Failover improvements • Event publication • Barge In • Others?
    • Thank You