He walked into dental offices to watch them break. Then he built the AI that answers when the front desk walks out.
Most founders chase the future. Abdul Jamjoom chased a busy signal.
Abdul Jamjoom runs Arini, a San Francisco company with a deceptively boring job description: answer the phone at the dentist. Behind that flat sentence sits one of the least romantic and most expensive problems in American healthcare. Dental practices in the US spend roughly $7 billion a year staffing front desks, and those desks - heads down, six hours a day on the phone - still miss about 35% of their calls. Every missed ring is a patient who didn't book, and at a dental practice an unbooked chair is real money walking out the door.
Arini is Jamjoom's answer: an AI voice agent that picks up around the clock, books appointments straight into the practice's existing software, talks through insurance and billing questions, and handles the texts too. He doesn't pitch it as magic. He pitches it as relief. "No one wants to be on the phone for seven minutes," he says. "Just get the job done."
That sentence is the whole philosophy. While much of the voice-AI industry races to sound human, Jamjoom optimizes for the opposite virtue: speed. Get in, get the appointment, get off the line. The receptionist nobody resents is the one who doesn't waste your afternoon.
You don't need four front desk hires. Hire one person to greet patients in the room - let the AI handle everyone calling in.
Jamjoom grew up between Saudi Arabia and Jordan. It was in a Jordanian high school that he met Rami Rustom, the person who would become his co-founder twice over. The two stayed close across continents and degrees - Jamjoom to Harvard for computer science with a lean toward natural-language research, Rustom to MIT for the same field. Harvard and MIT, one eventual company.
By his own account, Jamjoom treated his time at Harvard like a countdown clock. He was so eager to start a company that he resisted graduating, viewing every remaining semester as a delay between him and the thing he actually wanted to do. School was the waiting room. The build was the appointment.
After Harvard he joined Threads, a San Francisco enterprise messaging tool in the Slack family of products. He came in as a full-stack engineer and went deep on search and triage - the unglamorous plumbing of deciding which message matters and surfacing it fast. "One of the best investments was spending time figuring out search and triaging flows," he later reflected. He didn't know it yet, but he was training for a problem in a completely different industry: figuring out, in a flood of incoming calls, what a patient actually needs and getting them to yes.
At Threads he reunited with Rustom, and the two co-led applied-AI and automation work. When they left in late 2023, they left together - to find a problem worth their next decade.
Before dentistry chose them, Jamjoom and Rustom auditioned other worlds - charter bus companies, legal services, a handful of overlooked verticals. The research method wasn't a spreadsheet. It was walking in, shadowing the work, and feeling the pain in the room.
On one shadowing visit to a San Francisco dental practice, two of the four front-desk employees quit on the same day. The staffing crisis stopped being a statistic and became a scene. That afternoon is, more or less, the founding document of Arini.
What they learned is that the front desk is the real bottleneck for a dental practice's growth - not the dentist's chair, not marketing, the phone. Online booking exists, yet most appointments still get made by voice. So a ringing phone with no one to answer it isn't an annoyance; it's the ceiling on the whole business. Arini was built to lift that ceiling without asking a practice to hire its way out of a labor shortage that has no slack left in it.
It is tempting to think the difficulty in an AI receptionist is the voice. Jamjoom will tell you the voice is the easy part. The brutal part is scheduling. Dental practices run the same practice-management software in wildly different ways - what counts as a bookable slot at one office is forbidden at the next. A 30-minute gap might be a cleaning here and a hard no there. Multiply that across thousands of micro-rules per practice, across DSOs spanning the US and Canada, and you get an infrastructure problem disguised as a phone call.
So Jamjoom obsesses over latency and reliability with an engineer's discipline. When Arini found that Cartesia's Sonic voice model ran more than twice as fast as their previous provider, they switched - because in this business, milliseconds convert directly into patients who stay on the line instead of hanging up. The metric isn't how human it sounds. It's how few people give up.
Speed isn't vanity. Slower responses mean more hang-ups, and each hang-up can be a four-figure loss for the practice. Arini optimizes the gap between ring and answer like a trading firm optimizes a trade.
Rather than gatekeeping behind a support queue, Jamjoom has pushed Arini toward letting practices configure their own AI agents - their verbiage, their rules, their flows. Empowerment over dependency.
Meets Rami Rustom. The friendship that becomes a co-founding partnership.
B.A. in Computer Science, leaning into natural-language research. Treats graduation as a finish line he'd rather skip.
Full-stack engineer in San Francisco. Leads search and triage flows, then co-leads applied-AI work with Rustom.
Leaves Threads to co-found Arini.
Arini goes through Y Combinator's Winter 2024 batch, launches the AI receptionist for dentists, raises a seed round.
Talks shop on Deepgram's AI Minds podcast; Arini partners with Cartesia for low-latency voice; ships self-serve agent configuration.
Rami Rustom, the high-school friend turned co-founder, studied CS at MIT. Jamjoom did the same at Harvard. The rivalry schools, the same obsession - automating the work that quietly runs a business.
Arini is a Y Combinator company, with seed support from a roster that includes Transpose Platform, J17 Ventures, Sanabil and SBXi - betting that the dental phone is a market hiding in plain sight.
Where to find Abdul Jamjoom and the company he's building.