AMD Providers for Vicidial: KHOMP, Sangoma CPD, Stock Asterisk, and API Options Compared

If you run Vicidial, “which AMD should I use” usually gets answered with a cost comparison between CPaaS providers — Twilio, Telnyx, Plivo. That comparison is useful, but it skips a category that a lot of Vicidial shops already have sitting on their rack: gateway-based call progress detection from telecom hardware vendors, principally KHOMP and Sangoma CPD. Both are natively wired into Vicidial’s codebase, both predate most of the API-first options, and both do real work for real deployments. This post lays out what each option actually does, what it’s good at, and where it falls short — including AMDY’s own approach.

The options, at a glance

• KHOMP CPD — gateway/hardware-based call progress detection, first-class Vicidial support.
• Sangoma CPD (Call Progress Analysis) — SIP-proxy gateway product, requires a patched Asterisk (ViciBox ships pre-patched).
• Stock Asterisk app_amd — free, in-tree, no external dependency.
• API-based detection (AMDY and comparable services) — a streaming or REST call out to a classifier, billed per detection.
• CPaaS AMD add-ons — Bandwidth and Vonage bundle AMD into their voice APIs, useful mainly if you’re already routing calls through them.
• FreeSWITCH’s mod_avmd — the FreeSWITCH-world equivalent of app_amd, for shops on that stack instead of Asterisk.

This post covers the first four in detail, since those are the live decision for a Vicidial/Asterisk shop. For the CPaaS-lock-in cost tradeoff specifically (Twilio, Telnyx, Plivo), see our full comparison of AMD solutions for Vicidial and Asterisk and the individual writeups at Twilio AMD alternative, Telnyx AMD alternative, and Plivo AMD alternative — we won’t repeat that ground here.

KHOMP CPD

KHOMP is a Brazilian telecom hardware company founded in 1996, headquartered in Santa Catarina, with offices in Buenos Aires, Medellín, Mexico City, and Miami. Its call progress detection (CPD/AMD) doesn’t run as standalone software on your dialer box — it runs as a gateway-based service, where the SIP INVITE is routed through a KHOMP gateway or Flow server, and the gateway itself does the answer/human/machine classification before signalling the result back.

Vicidial has first-class, in-tree support for this: a campaign’s “AMD Type” setting can be set to KHOMP, with a “Routing Extension” (documented as 8368) plus CPD AMD Action and CPD Unknown Action parameters to control dialplan behavior. That’s documented directly in vicidial.org’s KHOMP CPD integration doc and referenced on vicidial.com.

What KHOMP is genuinely good at

• Official Vicidial integration. This isn’t a bolt-on plugin — the campaign settings for KHOMP ship in Vicidial’s own codebase, which is a lower integration-risk path than most third-party options.
• LATAM market presence. Twenty-plus years of carrier-grade E1/T1 and gateway hardware, with localized Spanish and Portuguese support and regional offices — a real advantage if your operation runs in Latin America.
• Carrier-grade hardware pedigree. KHOMP built its name on telecom gateway hardware, not on a software AMD add-on retrofitted later.

What we couldn’t verify

KHOMP does not publicly publish accuracy benchmarks or standard pricing for CPD, so we won’t guess at either. The one number that circulates is a single Vicidial forum thread where a user reported roughly 80% accuracy from KHOMP CPD alone, and said that number rose to over 95% when they ran stock Asterisk AMD alongside it. That is an unverified, single-operator forum report — not a vendor claim and not a benchmark. Treat it as one data point from one deployment, not a general accuracy figure for the product.

The gateway-based architecture also means CPD is tied to KHOMP hardware in the call path, which is a meaningful commitment compared to a software-only or API-based option. For a closer, dedicated look at how KHOMP compares specifically, see AMDY vs KHOMP and KHOMP alternative.

Sangoma CPD (Call Progress Analysis)

Sangoma CPD is a separate SIP-proxy gateway product from Sangoma, the company that owns and maintains Asterisk and FreePBX. It requires a patched Asterisk build to run — ViciBox images ship pre-patched, which is why it shows up as an option inside the standard Vicidial install path without extra work. It offers two result modes, DISPO and MESSAGE, and Sangoma’s own documentation recommends a cap of roughly 200 concurrent calls per quad-core server. Source: vicidial.com/?page_id=355.

What Sangoma is genuinely good at

• They own the platform underneath it. Sangoma maintains Asterisk itself and FreePBX, so a Sangoma-built AMD product has a real integration-story advantage — less risk of drift between the patched Asterisk and the analysis engine, since the same company ships both.
• Documented concurrency ceiling. A stated ~200 concurrent calls per quad-core server is more operational transparency than most gateway vendors publish.

What we couldn’t verify

Sangoma markets CPD with a claim of up to 95% accuracy. That is a vendor claim, not an independently verified benchmark, and we found no third-party measurement to check it against. We also could not confirm, from current sourcing, that CPD is still an actively sold and updated 2026 SKU — the documentation we found is older and undated. If you’re evaluating it today, verify directly with Sangoma or your ViciBox integrator that the product is current before committing to it.

Stock Asterisk app_amd

Stock Asterisk AMD needs no separate vendor at all. It’s in-tree, free, has no per-call fee and no network round trip, and every line of it is auditable. The official documented defaults, from Asterisk’s own amd.conf.sample, are:

Note that maximum_number_of_words defaults to 2, not 3 — that’s a common typo that circulates elsewhere on this topic, worth getting right if you’re tuning your own amd.conf.

app_amd sets AMDSTATUS to MACHINE, HUMAN, NOTSURE, or HANGUP, plus an AMDCAUSE explaining why. For a lot of shops, free-and-auditable is the right tradeoff, especially at low volume where a per-detection fee doesn’t pencil out. Its real limits — a two-and-a-half-bucket result, no separate category for carrier false answers or voicemail sub-types, timing-only heuristics — are covered in depth in the drawbacks of stock AMD and the parameter-by-parameter breakdown in the AMD terms glossary.

API-based detection

The fourth category is a streaming or REST API you call per detection, rather than software or hardware sitting in the SIP path. AMDY is one of these: an answering machine detection API for outbound telephony that returns a sub-second verdict over a streaming WebSocket or REST, with drop-in integrations for Vicidial, Asterisk, FreeSWITCH, and Issabel. Pricing runs from $0.00025 down to $0.00010 per detection at volume.

The honest tradeoff versus a gateway product like KHOMP or Sangoma: an API call means a network round trip and a per-detection cost that a fully on-box option like app_amd doesn’t have. What you get in exchange is a classifier that isn’t tied to specific gateway hardware, published (not vendor-claimed) methodology, and categories beyond human/machine/notsure. Whether that’s worth it depends entirely on your volume, your accuracy requirements, and whether misroutes are costing you agent time or lost contacts today. For the fuller cost-versus-alternatives breakdown across API providers, see best AMD solutions for Vicidial and Asterisk.

How to actually choose

• You already run KHOMP gateways, especially in LATAM. The native Vicidial integration and regional support make it a low-friction fit — just don’t take the 80%/95% forum figure as a guarantee for your own traffic.
• You’re on ViciBox with a patched Asterisk already. Sangoma CPD is worth evaluating, but confirm with Sangoma that the SKU is still current before you build a deployment around it.
• You want zero external dependency and low volume doesn’t justify a per-call fee. Stock app_amd is free, in-tree, and fully auditable — start there and measure your own NOTSURE rate before assuming you need more.
• Misroutes are costing you real money — dead agent time, wasted carrier minutes, missed live contacts. That’s when an API-based option with a published verdict methodology and per-detection audit trail starts to pay for itself. Start with the Vicidial AMD guide for the full integration picture.

None of these options is universally right. KHOMP and Sangoma both bring real, verifiable advantages — official Vicidial support, hardware pedigree, platform ownership — that a software or API-based product doesn’t automatically beat. Pick based on what you already run and what a wrong classification actually costs you, not on whichever accuracy number sounds biggest.

FAQ

Is KHOMP AMD/CPD supported natively in Vicidial?

Yes. KHOMP’s call progress detection is wired directly into Vicidial’s own codebase — campaigns have an "AMD Type" setting for KHOMP with a "Routing Extension" (documented as 8368) plus CPD AMD Action / CPD Unknown Action parameters. See vicidial.org/docs/KHOMP_CPD_INTEGRATION.txt. That first-party support is a real integration advantage over any third-party plugin, KHOMP included.

How accurate is KHOMP CPD?

KHOMP does not publicly publish accuracy benchmarks, so there is no vendor number to cite. The only data point we could find is a single Vicidial forum user report (vicidial.org/VICIDIALforum/viewtopic.php?t=38329) describing roughly 80% accuracy from KHOMP CPD alone, rising to over 95% when combined with stock Asterisk AMD running alongside it. That is one operator’s unverified forum post, not a benchmark — treat it as anecdote, not fact.

What is Sangoma CPD and is it still sold?

Sangoma CPD (Call Progress Analysis) is a SIP-proxy gateway product that requires a patched Asterisk build — ViciBox images ship pre-patched. Sangoma’s own marketing claims up to 95% accuracy, which is a vendor claim, not an independently verified figure. We could not confirm from current sourcing whether CPD is still an actively sold and updated SKU in 2026; the only documentation we found (vicidial.com/?page_id=355) is older and undated, so don’t treat it as current without checking with Sangoma directly.

What are the recommended concurrency limits for Sangoma CPD?

Sangoma’s own documentation recommends a cap of roughly 200 concurrent calls per quad-core server, and offers DISPO and MESSAGE result modes. That figure comes from vicidial.com/?page_id=355; we have not independently verified it against newer hardware.

Is stock Asterisk app_amd good enough for most Vicidial shops?

It is free, in-tree, has no external dependency and no per-call fee, and is fully auditable — for a lot of shops that is the right tradeoff. Its limits are well documented: it only judges HUMAN vs MACHINE vs NOTSURE from timing and silence heuristics, with no separate bucket for carrier false answers, voicemail sub-types, or spam traps. Whether that’s "good enough" depends on how much a misroute costs you. See our breakdown in the stock AMD drawbacks post.

False answer supervision and the other terms on this page are defined individually in the AMD glossary.