Telephony developer tools
Every listing tagged telephony, A to Z: 5 tools across 1 category. Listed in alphabetical order, not ranked.
Bland AI
Voice agent platform for phone calls with one per-minute rate that covers the LLM, speech-to-text and text-to-speech: Conversational Pathways for call flows, knowledge bases, version lock, your own Twilio or SIP trunk, and on-prem or VPC on Enterprise. Start plan $0.14 a minute with no platform fee and no card.
ElevenLabs Agents
ElevenLabs' hosted platform for voice agents: its own speech-to-text, your choice of LLM or a custom model, 10,000+ voices, a turn-taking model, a visual workflow builder, knowledge bases, tests and A/B experiments. Deploys to phone over Twilio or SIP, a web widget, or iOS, Android, React Native and Unity SDKs. Free plan with 15 call minutes; $0.08 a minute after that, LLM billed on top.
Retell AI
Platform for AI phone agents: a drag-and-drop call-flow builder, simulation and regression tests, outbound campaigns, live call monitoring with takeover, IVR navigation and CRM write-back, plus chat and SMS agents. Pay as you go at $0.07 to $0.31 a minute depending on model and voice, 20 concurrent calls included and $10 of free credit.
Synthflow
Enterprise platform for AI voice agents on customer calls, sold as one annual contract that covers telephony (Synthflow's own or SIP), CRM and calendar integrations, security review and launch by forward-deployed engineers. SOC 2 Type 2, ISO 27001, HIPAA and GDPR. No free plan or per-minute rate.
Vapi
Developer platform for voice agents that make and take phone calls: pick the transcriber, model and voice from dozens of providers, build single assistants or Squads that hand callers between specialists, test with simulations and manage config as code from a CLI. $0.05 a minute for Vapi hosting, with providers passed through at cost and $5 of free credit.