Member of Technical Staff

a1mobile; San Francisco (CA); Hybrid; USD 150,000 - 230,000; Full time

Job summary

a1mobile is building the AI-native carrier for businesses in the San Francisco Bay Area. This hybrid role sits in our SF office and requires you to work from the office a few days per week.

You will own the backend and voice/messaging infrastructure, building systems end to end from design to production. Strong Python/Async, FastAPI, and AI/LLM experience are essential for shaping our carrier platform.

Qualifications

• Proven experience building production backend systems with Python (async/await).
• Strong system and API design skills, and relational data modeling in SQL.
• Experience shipping AI/LLM-powered features to real users; ownership mindset.

Responsibilities

• Design and build backend services behind the AI receptionist (calls, messages, bookings, orders, quotes, follow-ups).
• Develop real-time voice AI pipelines (speech-to-text, LLMs, text-to-speech) with focus on latency and reliability.
• Collaborate with carrier infrastructure (voice, SMS/MMS, 10DLC, eSIM, provisioning).
• Create integrations and MCP connections to enable AI actions in customers’ tools (booking, ordering platforms).
• Evolve event-driven backend: durable ingestion, projections, replay.

Skills

Backend systems

System design

API design

SQL relational modeling

Ownership & collaboration

Tools

Python (async)

FastAPI

Next.js

React

TypeScript

Flutter

Dart

AWS

PostHog

Sentry

Job description

Member of Technical Staff · Hybrid, San Francisco Bay Area

This is a hybrid role based in our San Francisco office. You should live in the San Francisco Bay Area and be able to work from the office a few days a week.

About a1mobile

a1mobile is building the AI-native carrier for businesses.

We're rebuilding the carrier layer, bringing mobile, landline, and AI phone systems together. Every business number should answer, understand, take action, and follow up.

Our first product, a1mobile One, is one business line for $99/month: unlimited calls and texts, 5G data, and an AI receptionist built into the carrier itself. It answers every call and text 24/7, takes bookings and orders, sends quotes and follows up. Our customers are small service businesses: restaurants, cafes, salons, studios, contractors, and hotels.

We recently raised an $11.5M seed round led by General Catalyst, with backing from Menlo Ventures, SV Angel, Commerce Ventures, and other leading investors.

We're looking for a Member of Technical Staff to build the core of the AI-native carrier: the voice and messaging infrastructure, the AI agents that run on it, and the product our customers use every day. You'll own hard problems end to end, from system design to production.

• 4+ years of professional software engineering experience, with a track record of owning production systems end to end.

What you'll do

• Design and build the backend services behind our AI receptionist: calls, messages, bookings, orders, quotes, and follow-ups.


• Build real-time voice AI pipelines (speech-to-text, LLMs, text-to-speech) and push on latency, reliability, and call quality.


• Work directly with carrier infrastructure: voice, SMS and MMS, 10DLC messaging, eSIM, and number provisioning.


• Build integrations and MCP connections that let our AI take action in the tools our customers already use, like booking and ordering platforms.


• Evolve our event-driven backend: durable event intake, projections, and replay.


• Ship across the stack when needed, from our Next.js web app to our Flutter mobile app.


• Own reliability in production: monitoring, alerting, incident response, and performance.


• Backend: Python (async) with FastAPI


• Web: Next.js, React, and TypeScript


• Mobile: Flutter and Dart


• AI: LLMs, speech-to-text, text-to-speech, AI agents, and MCP integrations


• Infrastructure: AWS, Sentry, and PostHog

What we're looking for

• Strong experience building production backend systems, ideally in Python with async/await and FastAPI.


• Deep knowledge of system design, API design, and relational data modeling in SQL.


• Experience shipping AI or LLM-powered features to real users, not just prototypes.


• Comfort working across the stack, from infrastructure to the product surface.


• A strong sense of ownership and the ability to move work forward without waiting to be told.


• A team player who communicates openly, shares knowledge, and collaborates closely with others.


• The flexibility to adapt and keep pace with a fast-moving startup.

Nice to have

• Experience with real-time voice, streaming audio, or low-latency systems.


• Experience with Flutter and Dart, or with Next.js and React.


• Experience at an early-stage startup.

You'll work where telecom meets AI, making every call and message turn into real action for a business. The team is small, so what you build ships fast and matters to real customers.

a1mobile is an equal opportunity employer. Employment decisions are based on qualifications, merit, and business needs, without discrimination on any basis protected by applicable law. Pursuant to the San Francisco Fair Chance Ordinance, we will consider qualified applicants with arrest and conviction records for employment.