Voice agent pricing is quoted in two completely different units and vendors mix them freely, which is how a $300-a-month platform and an $80,000 custom build end up in the same conversation. There are two numbers: what it costs to build, and what it costs per minute to run. They behave differently and you need both.
1. Build cost by scope
| Scope | Build cost | Timeline |
|---|---|---|
| Single-flow agent on a managed platform | $4,000 - $12,000 | 2-4 weeks |
| Custom agent, LiveKit or Pipecat, in-app voice only | $12,000 - $25,000 | 4-7 weeks |
| Custom agent with telephony, tools and dashboard | $18,000 - $45,000 | 6-10 weeks |
| Migration off Vapi or Retell, with side-by-side comparison | $10,000 - $28,000 | 4-8 weeks |
| Multi-agent platform, several flows, admin and analytics | $45,000 - $120,000 | 3-6 months |
The variable that moves these numbers most is not the agent. It is integration surface: how many of your systems the agent has to reach, and how well documented they are. An agent that only talks costs a fraction of one that has to book, look up, update and escalate.
2. Running cost, per minute
| Component | Cost per minute | Notes |
|---|---|---|
| Speech to text | $0.004 - $0.011 | Deepgram at the low end, premium models higher |
| Language model | $0.008 - $0.040 | Depends on model and how much context you resend |
| Text to speech | $0.020 - $0.110 | Usually your largest line item |
| Telephony | $0.007 - $0.020 | Twilio at the high end, direct SIP lower |
| Platform fee | $0.050 - $0.100 | Managed platforms only; zero if you build |
| All-in, managed platform | $0.120 - $0.250 | |
| All-in, custom build | $0.040 - $0.110 |
The single most useful thing on this table: text-to-speech is usually more expensive than the language model. Teams optimise the model because that is where the attention is, and leave the actual cost driver untouched. Switching voice provider is often a bigger saving than switching model.
3. Where the break-even sits
The arithmetic is simple. If a custom build saves you roughly $0.10 per minute and costs $25,000, you need about 250,000 minutes to break even on the build alone, then add maintenance, which is real. At 10,000 minutes a month that is over two years. At 200,000 minutes a month it is six weeks.
This is why I tell most early-stage teams to stay on Vapi or Retell. The migration only makes sense when volume is real, or when the reason is capability rather than cost. I break that decision down in migrating off Vapi or Retell.
4. Costs that are missing from the first quote
5. How I quote
Fixed price when scope is clear, hourly when it is not, and always after a call rather than off a feature list. If a managed platform already solves your problem I will tell you that instead of quoting, because a client who migrates too early and regrets it is not a reference. Tell me what you are building and I will give you a real number, or see what AI voice agent development covers.