High Performance SIP Trunking / Termination Service using Metaswitch



Metaswitch and Oracle Communications (formerly Acme Packet) would love to own each other's customers; and many service providers own both.

This design shows how the two can be combined to make a scalable, high-performance SIP termination platform appropriate for outbound call centers.

High-performance call termination can be a challenge; many conventional systems, rich in SIP trunking features, aren't optimized for customers that each need 50 calls/second (cps).


  • Need for extremely high speed SIP termination, e.g., for large outbound call centers.
  • Oracle Acme Packet 4500 SBCs
  • Metaswitch CFS and MG3510 TDM VoIP to PSTN gateways
  • Service Provider has rich TDM and SS7 connectivity to various tandems on the PSTN
  • Geographically Distributed
  • Customer required to participate in scaling the traffic across multiple sites. This is the approach taken by all the major carriers for high-speed termination.

Key Design Features

  • Geographically Distributed System. The SIP trunk does not terminate to a single location, but rather to multiple locations.
  • The SBCs have their own failover capability, so that if the local Metaswitch CFS/MG3510 platform is overloaded, the SBCs have overflow routes to other carriers via SIP.
  • Exploits the fantastic capacity of the Metaswitch CFS and MG3510s.

Other Cool features

  • Each SBC is configured to limit the volume of traffic the customer may offer. For example, a customer that wants guaranteed no more than 50 CPS may be limited to 25 CPS at each of two sites. (For N+1 redundancy, add another site.)
  • We exploit the high performance of the Metaswitch CFS for call termination. These boxes are incredibly efficient at routing calls.
  • Calls are terminated to Metaswitch MG3510 TDM gateways. (Metaswitch now sells other models using their new CH6050 ATCA chassis, but there are many MG3510s in the field doing great work.) Each MG3510 has very high capacity, estimated here to be around 180 cps.
  • No one ordinary  64 kbps SS7 linkset can keep up with the total workload, so the MG3510s need multiple SS7 linksets.

Click to open the diagram for the full-sized version.