📞 SIP Trunking

Elastic, Encrypted Voice with E911/NG911 & Audit-Grade Control

SIP Trunking replaces legacy phone lines with IP-based voice trunks that scale on demand, encrypt media/signaling, and carry direct inward dial (DID) numbers—while preserving E911/NG911 compliance and enterprise-grade reliability.
SolveForce designs SIP trunks end-to-end—SBCs, TLS/SRTP, number management, fraud controls, QoS, and NOC monitoring—so your voice is clear, secure, and provably compliant.

Nearby pages:
☎️ PRI → /pri • 🧯 POTS Replacement → /pots • 🌐 SD-WAN → /sd-wan
🔐 Cybersecurity → /cybersecurity • 📊 SIEM / SOAR → /siem-soar

🎯 Outcomes (Why SIP with SolveForce)

  • Elastic capacity — burst or scale lines without pulling copper or ordering new PRIs.
  • Encrypted by default — TLS for signaling, SRTP for media; STIR/SHAKEN attestation for caller ID trust.
  • E911/NG911 ready — DID-to-location mapping, test-call artifacts, dispatchable location support.
  • Lower cost, higher control — consolidate trunks across sites; centralize routing/QoS and policies.
  • Audit-ready — CDRs, QoS/MOS, change approvals, and 911 evidence to SIEM.

🧭 Scope (What We Deliver)

  • Trunks & DIDs — local/toll-free DIDs, LNP (port-in), CNAM, international routes (policy-gated).
  • Session Border Controllers (SBCs) — topology hiding, NAT traversal, TLS/SRTP termination, rate-limit & DoS protections.
  • E911/NG911 — location database, dispatchable location, test calls with recordings and PSAP confirmations.
  • Redundancy — multi-region SIP trunks, dual SBCs, diverse Internet/underlays (fiber + coax + LTE/5G).
  • Interoperability — PBX (legacy & IP), UCaaS/CCaaS, analog gateways (FXS) for elevators/alarms/fax.

🧱 SIP Building Blocks (Spelled out)

  • Signaling / Media — SIP over TLS (TCP/5061), SRTP (AES-GCM); fallback G.711u/a; optional Opus for wideband.
  • Codecs — G.711 (toll quality), G.729 (bandwidth save), Opus (wideband); SDP policy & transcoding at SBC as needed.
  • Fraud controls — dial plan allow/deny lists, international policy, per-destination limits, call velocity, geo/ASN rules.
  • QoS — EF for voice, AF classes for signaling; DSCP marking end-to-end; SD-WAN policy steering.
  • Recording / Compliance — selective record integrations, lawful intercept procedures (policy-controlled).
  • Fax & TTY — T.38 or G.711 pass-through validated per site; test matrices included.

🛠️ Design Patterns (Pick your fit)

A) Legacy PBX → SIP Gateway (Phased Migration)

  • Keep your PBX; insert PRI↔SIP gateway; cut sites/users in waves; preserve all DIDs.
    → /pri

B) IP PBX / UCaaS with Dual Trunks

  • Dual SIP trunks to separate providers/regions; dual SBCs; policy-based route & failover; SRTP/TLS enforced.

C) Contact Center / IVR

  • Multiple DNIS, intelligent routing, call recording & analytics; SBC protects edges; QoS per queue; capacity on demand.

D) Campus & Analog Devices

  • Central FXS gateways for elevators/alarms/fax; SIP backhaul; UPS runtimes documented; monthly test calls logged.
    → /pots

E) Branch WAN with SD-WAN

  • Voice flows pinned to loss/jitter SLOs; path duplication for critical calls; brownout steering to the healthiest underlay.
    → /sd-wan

🔐 Security & 911 (Concrete, enforceable)

  • TLS/SRTP end-to-end; SBC certificate management; cipher policy; STIR/SHAKEN signing/verification.
  • SBC hardening — topology hiding, strict SIP ALG avoidance, rate-limit & DoS detection, fraud throttles, geo/ASN blocks.
  • Identity & access — SSO/MFA to admin portals; RBAC for changes; config in Git with approvals.
  • E911/NG911 — DID→address mapping, per-floor/room where required; test call recordings & PSAP confirmation archived.
  • Logging — CDRs, QoS/MOS, SBC events, config diffs → SIEM; SOAR playbooks for auto-block/rollback.
    → /siem-soar

📐 SLO Guardrails (Targets you can measure)

KPI / SLOTarget (Recommended)
Call setup time (post-dial delay)≤ 1–2 s local, ≤ 2–4 s long-haul
MOS (wideband / narrowband)≥ 4.1 / ≥ 3.9
One-way latency≤ 50 ms metro, ≤ 120 ms continental
Jitter (one-way)≤ 20–30 ms
Packet loss (sustained)< 0.2–0.5%
Trunk availability≥ 99.95–99.99% with dual routes
E911 provisioning accuracy= 100% of DIDs, with confirmed test
Evidence completeness100% (CDR/QoS/changes/911 tests)

SLO breaches open carrier tickets and trigger SOAR actions (reroute, throttle destination, rollback policy).

⚙️ Networking & QoS Notes

  • Underlays — fiber/coax/DSL/LTE/5G; SD-WAN steers on loss/jitter; packet duplication for critical paths.
  • NAT & firewalls — avoid SIP ALG; pin SBC IPs; open only required ports; use TLS-only trunks.
  • DNS & SBC FQDNs — geo-redundant SRV with health checks; fast failover verified in drills.
  • MTU/MSS — size for SRTP + tunnels if using IPsec; avoid fragmentation.

📊 Observability & NOC

  • Real-time: trunk state, call attempts, ASR/ACD, MOS/Jitter/Loss/Latency, codec mix, fraud alerts, SBC CPU/conn counts.
  • Dashboards & monthly reports; carrier escalation runbooks held by NOC.
    → /circuit-monitoring • /noc

💵 Commercials (What drives cost)

  • Trunk concurrency (channels/sessions), DID/TN counts, toll-free, international policies.
  • E911/NG911 services, CNAM, LNP porting fees; call recording/analytics add-ons.
  • Term (12/24/36 mo), NRC for install, MRC per trunk/DID; optional managed SBCs.

🧪 Turn-Up & Acceptance (What we test)

1) SBC & trunk registration — TLS certs, SRTP policy, routing.
2) Inbound/outbound call plan — local/LD/toll-free; international per policy.
3) QoS/MOS baselines — synthetic & live call tests; packet captures archived.
4) Failover — primary→secondary trunk, SBC HA, SD-WAN path shift.
5) 911/NG911 — live PSAP test; address/ELIN validation; record confirmations.
Artifacts (CDRs, captures, PSAP confirmations, configs) exported to SIEM.

✅ Pre-Engagement Checklist

  • ☎️ Current trunks (PRI/SIP), PBX/UC platform, site dial plans.
  • 🔢 Channels (busy-hour), DID inventory, toll-free; international policy.
  • 🆔 911/NG911 dispatchable locations; test-call windows per site.
  • 🔐 SBC presence (vendor, licenses) or need managed SBC; TLS/SRTP readiness.
  • 🌐 Underlays (fiber/coax/LTE/5G), SD-WAN policy, QoS classes.
  • 📊 Monitoring destination (SIEM), reporting cadence, escalation tree.

🔄 Where SIP Trunking Fits (Recursive View)

1) Grammar — voice rides Connectivity underlays (fiber/coax/DSL/LTE/5G