Spend Control for Voice Agents
Voice agents are the fastest-growing agent category — and the easiest to overspend on: every call bills minutes, and every turn bills tokens.
Where voice agents spend
Telephony minutes per call — including failed and retried calls.
LLM tokens per turn across long or looping conversations.
Tool calls triggered mid-call (lookups, bookings, payments).
Platform fees on top (Vapi, Retell, Bland).
The failure modes
A retry storm of failed calls bills minutes for nothing.
Long conversations compound tokens per turn.
Voice campaigns scaling without a budget ceiling.
Which rules to start with
Per-call or per-day telephony ceiling.
Category rule: telephony vs inference.
Velocity limit on retries.
Merchant allowlist for voice platforms and tools.
Spend map
| Voice spend | Control |
|---|---|
| Telephony minutes | Per-call / daily ceiling |
| LLM tokens | Category budget |
| Mid-call tools | Merchant allowlist |
| Retries | Velocity limit |
FAQ
Can I cap per campaign?
Yes — per-agent rules per campaign or use case.
Does the firewall slow call setup?
No — ~5 ms per check, spend actions only.
Related
Stop the next $12,400 night.
One API call (or MCP tool) in front of every agent transaction — APPROVED, BLOCKED, or FLAGGED, deterministic, ~5 ms, fully logged.
See plans — from $99/mo Try a live check