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Rounds/Retell/Customer Success Engineer·#11798
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AI·Series A·Redwood City, California

Customer Success Engineer

at RetellAI
Location
Redwood City, California
Salary
$135,200 - $156,000
Type
Full-Time
About Retell
Retell AI is building the modern CX platform for enterprise contact centers, using first-principles voice AI to automate sales, support, and logistics calls at scale. Thousands of companies—including CVS/Aetna, American Airlines, Lenovo, and Grab—use Retell's AI voice agents to replace large teams of human agents, with the platform powering everything from frontline agents to QA analysts and managers. Backed by Y Combinator (W24), Alt Capital, and Carya Venture Partners, Retell claims $80M ARR as of August 2026 (public data: $60M+ as of April 2026), up from $5M at the start of 2025, and a valuation north of $1.5B. The team is 50 strong, with alumni from Stripe (payments lead), Google AI research, and Facebook product. The company has been recognized as a top AI app by a16z, #3 Fastest-Growing Software Company (G2 2026), and a member of the Nasdaq & Wing VC Enterprise Tech 30 (2026). The vision: a fully AI-powered contact center where intelligent agents continuously execute, monitor, and improve every customer interaction—no more basic automation that needs constant human tuning. The market believes: Retell is the fastest-growing voice AI company in the category, with real revenue, enterprise traction, and a reputation for technical depth.
Series A • 51 – 200
Stage & size
AI
Industry
2023
Founded
About This Role

The mandate: Serve as the technical partner for enterprise customers deploying and scaling AI voice agents in production — integration design, troubleshooting, workflow building, and expansion from onboarding onward.

The role sits at the intersection of software engineering, customer success, and AI deployment. Works with Engineering, Product, and Customer Success internally, and directly with customer engineering teams.

Relationship to the Applied AI Engineer req (same department):

Applied AI Engineer****Customer Success EngineerComp$200–300K + meaningful equity$65–75/hr, no equityEmploymentFull-time employee1099 or W-2 contractExperience2+ years5+ years CS/CSE, or recent top-tier gradInterview loopNot statedNot stated

Responsibility lists overlap substantially: technical onboarding, debugging across APIs/webhooks/SIP/telephony/auth/latency, working in customer codebases, product feedback, expansion. Confirm with Retell how the two seats are distinguished.

Experience requirement is a barbell: either 5+ years in Customer Success or as a CSE at a B2B software company, or a recent graduate from a top-tier university with a relevant technical degree. No middle band specified.

What You'll Own

Enterprise customer deployments

  • Lead technical onboarding for enterprise customers
  • Primary technical point of contact throughout implementation
  • Drive successful launches and product adoption
  • Build relationships with customer engineering teams

Technical consulting

  • Build AI voice agents alongside customers
  • Design conversation flows and deployment strategies
  • Troubleshoot production deployments
  • Debug APIs, webhooks, SIP, telephony, authentication, integrations, and latency issues
  • Work directly inside customer codebases when necessary

Product partnership

  • Identify product gaps through customer feedback
  • Translate customer needs into actionable product improvements
  • Partner with Product and Engineering; advocate for customers in the development process

Customer growth

  • Identify expansion opportunities
  • Help customers launch new AI use cases
  • Increase adoption across organizations
  • Serve as trusted technical advisor for enterprise accounts

Requirements

Hard gates:

  • Bachelor's in CS, CE, EE, or a related technical field
  • One of: 5+ years in Customer Success or as a CSE at a B2B software company, or recent graduate from a top-tier university in a relevant technical field
  • Strong technical problem-solving skills
  • Experience working with APIs and debugging technical issues
  • Excellent communication; able to explain technical concepts to customers
  • Available for standard U.S. business hours in Pacific or Eastern time, with sufficient Pacific overlap

Nice to have:

  • Python or TypeScript
  • AI, LLM, or voice AI experience
  • Startup experience
  • Enterprise customer support experience
  • Willingness to travel up to 10% for launches, workshops, and Innovation Day events

Not listed but recurring in the responsibilities: telephony, SIP, and real-time communications experience appears throughout the debugging scope.

Anti-patterns

  • Traditional CSMs with no debugging ability — the role works inside customer codebases
  • Support engineers who escalate rather than diagnose
  • Candidates who require full-time employment, benefits, or equity
  • Candidates with comp expectations at the Applied AI Engineer band
  • Candidates with 2–4 years of experience — excluded by the barbell as written
  • Candidates outside Pacific or Eastern time zones

Who Will Thrive Here

Either an experienced CSE working on contract terms by preference, or a recent technical graduate. Both need debugging depth, direct customer communication ability, and comfort working in unfamiliar codebases under production pressure. The JD's framing: "You like building alongside customers instead of just supporting them" and "You're comfortable debugging complex systems under pressure."

Job Details
Experience
2-8 Years
Salary
$135,200 - $156,000
Visa Sponsorship
No
Employment Type
Full-Time
Work Arrangement
Hybrid
Work Intensity
9-5-5
Benefits & Perks
$75/month Phone Bill Reimbursement
$50/month Internet Reimbursement
$70/day Doordash Credit For Unlimited Breakfast Lunch Dinner And Snacks(not Included If Remote)
$200/month Wellness Reimbursement(gym Fitness Classes Etc.)
$300/month Commuter Reimbursement(gas Caltrain Etc.)
Medical Dental And Vision Insurance
Green Flags
5+ years in customer-facing technical roles at B2B SaaS companies
Experience deploying or supporting AI/LLM/Voice AI products
Strong API debugging and integration skills
Red Flags
Pure support background with no technical depth
No experience debugging APIs or integrations
Uncomfortable working directly with customer engineering teams
Ideal Companies
T
Twilio
I
Intercom
K
Kore.AI
J
JustCall
S
Synthflow

Required Candidate Q&A

Question 1
Are you based in the US and able to work standard US business hours (Pacific/Eastern), with overlap to a Pacific Time–based team?
Question 2
What is your visa status and earliest possible start date?
Question 3
Describe your experience supporting enterprise customers in a technical capacity. What was your most challenging deployment?
Question 4
Walk through a time you debugged a complex API or integration issue for a customer. What was the root cause and how did you resolve it?
Question 5
Have you worked directly inside a customer’s codebase or production environment? What did you learn from that experience?
Question 6
What’s your experience with AI, LLMs, or Voice AI products (if any)?
Question 7
Why Retell? What about building the future of voice AI and customer experience excites you?

Candidate scorecard

· 11 criteria
Bachelor's in CS, EE, or related technical field
5+ years in Customer Success Engineering at a B2B software company, or recent grad from a top-tier technical university
Strong technical problem-solving skills
Rounds · Confidential to recruiting partners · Last refreshed Aug 21, 2026