Voice across the whole lifecycle
Speed-to-lead and 24/7 inbound sales agents, loan-officer appointment booking, and FDCPA-compliant servicing and collections — borrower conversations from first contact through payoff, on one platform.
Comparison · Voice Agents
Sei vs Kastle
Kastle focuses on AI voice agents for mortgage servicing. Sei covers servicing and origination voice and adds the loan manufacturing in between — underwriting, income calculation, closing, and QC — on one managed platform.
The short version
Kastle and Sei both run compliant AI voice agents for borrower calls, and both target mortgage. Kastle concentrates on the servicing side — payments, escrow, retention, and early-stage collections — across multiple channels.
Sei runs voice across the whole lifecycle and pairs it with the loan operation. Servicing agents handle payoffs, due-date changes and FDCPA-compliant hardship calls. Origination agents run speed-to-lead and book loan-officer appointments. The same managed platform underwrites the file with rep-and-warrant-eligible income, automates the Closing Disclosure and clears post-close QC.
The frame
A point solution automates a step. A desk owns the outcome.
Most of the vendors on this page automate one step. The question that decides the buy is what happens when that step is done: a tool hands its output back to a queue, and someone has to pick it up. A desk holds the goal until it is reached, and tells you where it stopped.
You buy a step
Extraction, or an application form, or a review pass. It runs when someone runs it, and hands the result to the next queue.
You staff a desk
It holds a goal across weeks, wakes when the loan moves, re-plans when the file changes, and escalates by name when it is below its confidence floor.
Each tool has its own copy of the loan
So there is a reconciliation step, and a version of the file only one vendor can see.
One live model of the loan
A condition created by underwriting is visible to the document desk in the same instant, because there is only one of it.
Coverage is the sum of your vendors
Eight vendors, eight handoffs, and the cycle time lives in the gaps between them.
Coverage is the length of the loan
Lead call to clear-to-close, boarding to payoff, against one version-controlled rulebook.
Sei vs Kastle, at a glance
| Capability |  | Kastle |
|---|---|---|
| Servicing & collections voice (FDCPA) | Yes | Yes |
| Inbound sales + speed-to-lead voice | Yes | Limited |
| Loan-officer appointment booking | Yes | No |
| 100% call QA (TILA/RESPA/TRID) | Yes | No |
| Document intelligence & underwriting | Yes | No |
| Income calc + Fannie Income Calculator (rep & warrant) | Yes | No |
| Closing Disclosure automation & post-close QC | Yes | No |
| End-to-end coverage | Sales → servicing | Servicing voice focus |
Comparison based on each vendor’s public materials as of June 2026. Competitor capabilities and claims are theirs; we aim to keep this fair and accurate — if anything is out of date or wrong, let us know.
What those rows mean
Rep-and-warrant-eligible income
Income is calculated across W-2, self-employed (Schedule C, K-1, S-corp, 1099), rental, and retirement income, with Fannie Mae Income Calculator integration — so eligible calculations earn representation-and-warranty relief and lower repurchase risk.
Fully managed, end to end
Sei builds, deploys and runs the agents and workflows for you — from the first sales call through underwriting, closing and post-close QC. Managed means Sei runs the system, not that a services team works your files behind it. Every decision is machine-made, confidence-scored and cited, and the automation rate is a number you can hold Sei to.
The case for Sei
When Sei is the better fit
- You want voice on both origination and servicing from one platform
- You also need underwriting, income calculation, closing and QC
- You want 100% call QA against TILA, RESPA, TRID and UDAAP
Frequently asked questions
Is Sei a fit for mortgage servicing like Kastle?
Yes. Sei’s voice agents handle servicing calls — payments, payoffs, due-date changes, hardships, and FDCPA-compliant collections — and also cover origination, underwriting, closing, and QC on the same managed platform.
Does Sei integrate with servicing systems?
Yes. Sei integrates out of the box with CRMs and telephony/CCaaS platforms, and with the LOS you originate in — ICE Encompass, Calyx and MeridianLink. Servicing systems of record are supported through custom integrations during onboarding.
What does Sei add beyond servicing voice?
Origination sales voice with LO appointment booking, document intelligence and underwriting, income calculation for rep-and-warrant relief, Closing Disclosure automation, and pre/post-close QC.
What certifications does Sei hold?
Sei is SOC 2 Type II and PCI DSS Level 1 certified, deploys in private VPCs, and never trains on your data.
More comparisons
Document Intelligence
Sei vs Gateless
Gateless automates underwriting condition clearing inside your LOS. Sei runs the file end to end — pre-underwriting through post-close QC — fed by borrower-facing voice agents.
Read comparisonCall Monitoring
Sei vs Observe.ai
Observe.ai is a horizontal contact-center AI suite sold across many industries. Sei is a fully managed platform built for mortgage lenders and servicers — speed-to-lead, LO appointment booking, FDCPA servicing, 100% QA, and the loan manufacturing behind the calls.
Read comparisonVoice Agents
Sei vs Genesys
Genesys is the enterprise contact-center platform you build and configure on. Sei is a fully managed mortgage platform that runs on top of Genesys — borrower voice plus underwriting, closing, and QC.
Read comparisonYou Ain't Seen Nothin' Yet
Book a Demo
Pack up some of your complex historical files — any loan type, any investor. We run them through intake, income and condition clearing, and in 30 minutes you see every condition we created and cleared efficiently for your own team, and why.
- Any loan type, any agency guideline or custom investor overlays.
- Every finding cited to the guideline or document it came from