The Five Layers (and one overlay)
Every enterprise voice setup is a stack. From the spectrum-owning carrier at the bottom to the agent's screen-pop at the top, the layers are remarkably consistent across every customer you will meet — what changes is which vendor fills each layer. Click any layer to expand its role and the major vendors.
Who builds what
Three rules of thumb. Cisco / Avaya / Genesys are the "big three" full-stack contact-center vendors — they own Layers 4 + 5 in most large enterprises. AudioCodes / Oracle / Sonus are SBC specialists — Layer 3. NICE / Verint dominate recording, QM, and WFM — workflow add-ons that bolt onto any of the big three.
Session Border Controllers
Translate, secure, and policy-enforce at the edge. Often a hardware appliance in regulated industries.
IP-PBX / Voice Gateway
Internal call routing. The "phone system" that makes extensions and hunt groups work.
Full Contact Center Suites
ACD + CTI + agent desktop + recording, all in one. The "big three" are battle-tested, expensive, and politically embedded.
Standalone IVR / Voice Browser
When the IVR is its own product, separate from the PBX. Cisco VVB is the one you'll see most in TR enterprises.
Recording & QM
Captures every call, stores it, scores it for compliance and quality. Bolts onto any of the big three.
Workforce Management (WFM)
Forecasting + scheduling + adherence for the human agent fleet.
SIP Trunk Providers
Resell PSTN over IP. Some are TR-local (Verimor, Connecta); others are global (Twilio, Bandwidth/Voxbone, Telnyx).
BPO Operators
Third-party contact-center operators. They run Layers 4 + 5 for large brands that don't want to operate their own call center.
How a phone call actually reaches an agent
An inbound call has the longest journey of any product interaction in the enterprise. Step through it once, end-to-end, and you will recognize every hop in every customer meeting from now on. Then flip the variant: see exactly where Freya replaces a layer.
What we are, and what we are not
Freya is an agent runtime + workflow builder. We are not a PBX, not an ACD, not an IVR, and not a CRM. Knowing this sharply is the difference between a productive customer-IT meeting and a confusing one.
We do not own extensions, hunt groups, voicemail, or queueing. We run AI voice agents inside the slot the customer already gives a human agent.
We connect either to the customer's SBC (enterprise topology) or directly to a SIP trunk provider (greenfield / SMB topology). One or the other — never both for the same trunk.
For outbound campaigns and inbound triage, the call lands on a Freya endpoint instead of a human agent desktop. Most common deployment shape.
For inbound first-touch, the trunk hands the call directly to Freya before any customer ACD sees it. Used when self-service ("balance check", "outage status") would replace a DTMF menu entirely.
Every customer has signaling, codec, and header quirks. Cisco UCCE proxies bypass Record-Route; Genesys SBC silently enforces TCP; carriers add or strip + prefixes. The signaling spec is generic. Production never is.
Outcome write-back, contact list, customer record — all in the customer's CRM. We expose webhooks and APIs; we don't own the data. Always confirm who owns the dialer, who owns the disposition codes.
Where each customer fits the stack
Four real Freya deployments, mapped onto the Five Layers. Click a customer to see exactly which vendor fills each layer for them — and which layer Freya replaces.
Allianz Türkiye
31.155.2.249.9015) that Asterisk must prepend to dialed numbers, or the call routes to the wrong destination.Garanti BBVA
Record-Route, so once the dialog is established, ACK and BYE bypass the proxy and go UA-to-UA between Asterisk and VVB. The customer firewall opened 5060 only on the proxy path — every call dropped at exactly 60 s. Fix: open UDP 5060 directly between VVB and Asterisk in the firewall.Anadolu Sigorta
5001 outbound · 5002 inbound · 5003 outbound-transfer · 5004 inbound-transfer.tcpdump. (A4) Genesys's X-Genesis-* custom headers contained Turkish characters in the field name (not value). PJSIP silently dropped the entire INVITE. ASCII-only header names from then on.KKB / Kloudeks — the simplest topology
194.49.126.26.kkbfcfreyasrv01; 4× H100 NVL; Gemma LLM.The acronyms you will hear in every meeting
Twenty terms. If you can define each one in a sentence, you are fluent enough to navigate any customer-IT conversation about voice. The acronyms collide with networking terms (CLI, CDR), so context matters.
A customer's IT lead says: "We're on Cisco UCCE end-to-end with KASP at the edge in light mode. Our SBC handles transcoding, but the trunk to Verimor is on a separate path." How many of those terms map to which layer of the stack?
Show answer
UCCE = Layer 5 (contact-center suite). KASP = Layer 3 / SIP proxy at the edge. SBC = also Layer 3, may be the same box as KASP or a separate appliance — ask. Verimor trunk = Layer 2. Light mode = the Garanti M08 trap; KASP won't insert Record-Route, so ACK/BYE will bypass it; you must open 5060 directly between VVB and your Asterisk. The customer just told you their Layer 3 + Layer 5 vendors and a known trap. Start the conversation from there.
You can now walk into any customer's IT meeting and recognize every layer.