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Domain Examples/SIP Trunk / Hosted Voice

SIP Trunk / Hosted Voice

End-to-end flow for provisioning enterprise SIP trunking across 5 office sites, from enquiry and feasibility through SBC provisioning, number allocation, ENUM configuration, number porting (LNP/MNP), call testing, mediation setup, and ongoing voice quality monitoring.

Architecture Overview

SIP trunking replaces legacy ISDN/PRI circuits with IP-based voice connectivity. The enterprise PBX connects through a Session Border Controller (SBC) that secures all SIP traffic with TLS/SRTP. On the provider side, a softswitch handles call routing and number translation via ENUM, before connecting calls onward to the PSTN, mobile networks, or other operators.

Enterprise EnvironmentCustomer-ownedConnectivityOperator-managedService Provider NetworkOperator-ownedExternal NetworksInter-carrierIP Phones / Soft ClientsPoE handsets, desktop/mobile appsTeams / UC PlatformEnterprise PBXCUCM / Avaya / MitelEnterprise SBCTLS / SRTP / NAT / CACOperator-supplied CPESecure SIP TrunkIP / MPLS / VPNDSCP EF + CS3Access circuit includedProvider SBCPolicy / Topology HidingSoftswitch / IMSCall Routing / ServicesNumber Mgmt / ENUMMediation / CDRPSTNTDM / SIP InterconnectMobile NetworksVoLTE / CS FallbackSIP InterconnectsOther Operators / OTTInterconnect SBCPeering / TranscodingLNP / Portability

Enterprise Telephony

IP phones, soft clients, and UC platforms (e.g. Teams) connect to the PBX, which handles internal routing and sends external calls to the E-SBC.

Enterprise SBC

Demarcation between enterprise and provider. Secures SIP with TLS/SRTP, manages NAT traversal, enforces call admission control, and hides internal topology.

SIP Trunk

IP transport between E-SBC and provider edge over MPLS, VPN, or internet. Requires QoS marking (DSCP EF for media, CS3 for signalling) and <150 ms latency.

Provider Voice Core

Provider SBC terminates the trunk; softswitch (BroadWorks/Metaswitch) handles call routing, ENUM translation, supplementary services, and CDR generation.

External Interconnect

Calls routed to PSTN, mobile, or other operators via I-SBC. Number portability databases (NPAC/LSMS) ensure ported numbers reach the correct carrier.

Provisioning Workflow

Step-by-step orchestration flow — click any step to view systems, inputs/outputs, and eTOM mapping.

Interactive Flow Steps

BSSOSSPartnerBSS+OSS

Tap any step to view details, systems, and eTOM mapping.

Step-to-eTOM Mapping

eTOM L2 CapabilitySteps
CRM & Retention Management
Order Handling
Resource Provisioning
Service Configuration & Activation
Service Quality Management
SM&O Support & Readiness
Billing & Revenue Management