Phone Stack is AI calling software that automates outbound customer contact from start to finish. Set a campaign goal, upload your contact list, and your AI voice agent calls each contact, handles the conversation naturally, and takes action automatically — sending emails, booking meetings, or firing webhooks to update your systems. Designed for teams running high-volume automated outbound calls without the cost of human agents. Phone Stack customers use it for collections follow-up, appointment reminders, delivery notifications, and sales lead qualification. Early users cut inbound call volume by 40% and improved collections rates by 35% using proactive AI outreach. Every campaign runs on frontier AI models including Claude and GPT, paired with enterprise telephony infrastructure. Call recording, AI summaries, and outcome tracking are included on all plans. Compliance features — TCPA consent tracking, opt-out handling, AI caller disclosure, and audit logs — are built into the platform, not sold as add-ons. Pricing is per minute of talk time, starting at $0.25/min, with no seat fees and no contracts. New accounts receive 30 free minutes. No credit card required to start.