The 7 hidden costs of CPaaS voice pricing
Per-CPS fees, minute roundups, E911 add-ons, and other line items your CPaaS won't highlight when you sign up.
1. Per-CPS fees
Calls-per-second provisioning is close to free on the carrier side — it's a soft limit in a switch config, not a physical resource — but CPaaS vendors charge anywhere from $0.50 to $1.00 per CPS per month as if it were dedicated hardware. Twilio's programmable voice lists this as "Dedicated CPS" at $0.75/CPS/month; Telnyx caps base CPS at 30 on Launch tier and requires a Pro upgrade to raise it. For a contact center running 300 CPS across a multi-campaign day, that's $225–300/month on top of the per-minute rate, for something the underlying carrier provisions in a single SIP NOTIFY to raise the trunk's concurrent-call limit. We don't meter CPS at all. Burst to whatever your switch can originate — our capacity test rig handles 2,400 CPS sustained — and you won't see a surcharge. See /pricing/cps/ for the longer breakdown of why this line item exists and what it's actually covering.
2. Minute rounding up
60-second billing increments are the most common invisible tax on voice traffic. A 3-second auto-terminated call (busy, no-answer, voicemail rejected) gets billed as a full minute; a 31-second successful connect also gets billed as a single minute but could have been 31 seconds of actual cost. For a predictive dialer running a 30% connect rate with average-talk-times of 40 seconds plus 70% short drops, the rounding adds roughly 30–40% to the voice spend compared to second-accurate billing. Twilio, Bandwidth, and Vonage all round 60/60 by default. We bill 6-second minimum then 1-second accurate, which matches the ITU standard for carrier interconnect. If your CPaaS doesn't publish its billing increment in the rate card, it's almost certainly 60/60 — pull one month of CDR, sum the second-accurate durations, and compare to what was billed.
3. Tier-A STIR/SHAKEN surcharge or silent downgrade
STIR/SHAKEN attestation level is the single biggest determinant of answer rate on US/CA outbound. A-level attestation says the originating carrier owns the number and verified the customer; B-level says the carrier knows the customer but doesn't own the number; C-level is just "this call came through our gateway." Downstream analytics (First Orion, Hiya, TNS) weight these heavily — B-level traffic is 15–25% more likely to be flagged as Spam Likely than A-level traffic from the same origin. Some CPaaS charge extra per-call to sign at A-level; others silently sign at B by default and describe the calls as "signed" in their marketing. Paste any SIP Identity header into the verifier on /stir-shaken/ and you'll see what tier your current carrier is actually signing at. We sign A on every eligible US/CA call by default, no surcharge.
4. E911 monthly fee per DID
E911 and Ray Baum's Act compliance are federal requirements — the originating carrier must be able to route emergency calls to the correct PSAP with a dispatchable address. CPaaS routinely charges $1–$2 per DID per month as an E911 "service fee," which turns a statutory obligation into a product upsell. Over a 1,000-DID contact-center deployment, that's $12,000–24,000/year for a feature that the carrier is legally required to provide whether you pay for it or not. Twilio lists this as "Emergency calling registration" at $1/number/month; Bandwidth bundles it into per-location fees that can reach $5/month per address. We include E911 and the dispatchable-address registration in the base $5/DID/month — if you need to update the address (common for contact-center agents who move desks), the update is a REST call, not a billable event.
5. Inbound minute premium
Inbound minutes cost the carrier substantially less to terminate than outbound minutes cost to originate — the terminating carrier typically earns an access charge from your originating carrier, which means inbound should cost you less, not more. CPaaS vendors routinely charge symmetric rates ($0.0085 outbound and $0.0085 inbound is common on Twilio's mid-tier plan) or even invert the ratio on specific plans. On a 1M-minute/month contact center with a 30/70 outbound/inbound split, the inbound premium is the biggest single line item after the per-minute rate itself. Pull your last three months of invoices and compare the per-minute cost by direction. If inbound is within 10% of outbound — or higher than outbound — you're paying carrier-margin fees on traffic that arrives with positive revenue to your carrier already built in. Our inbound rate is $0.0060/min on US/CA against $0.0100/min outbound, which approximates the actual cost gap.
6. Burst / overage surcharges
Predictive dialers don't generate smooth traffic — they burst. A campaign kickoff at 9am pushes 5× your baseline CPS for 20 minutes while the hopper fills, then settles. CPaaS plans treat bursts as overages: either the vendor rate-limits you (returning 503s to your dialer, which kills the campaign for as long as the throttle holds) or they allow the burst and bill it at a per-call surcharge that adds 15–40% to the daily spend. Twilio's Elastic SIP Trunking documentation lists "Channel Concurrency" overage at $0.001 per concurrent channel per minute above the plan cap; that's $9/hour per channel over the cap on a busy hour. Our trunks carry whatever you send — no rate-limiting, no overage surcharges, no "please upgrade to burst above 100 CPS" emails from account management. If your switch can originate it, our infrastructure carries it.
7. 'Enterprise tier' discount unlocking
The per-minute rate published on a CPaaS website is the retail price. The real rate — often 30–60% lower — requires a signed committed-use contract with minimums that start at $5k-$10k/month and climb from there. If your volume is between $500/month and the enterprise minimum, you're paying retail forever, while your larger competitors pay half what you do for the exact same service. This pricing model is structurally opaque on purpose: the retail card is the anchor, the enterprise negotiation is the real market, and the gap is where the margin lives. Our rate deck is the rate deck — one price tier, published quarterly with a 30-day notice window on changes. Volume discounts kick in automatically at $3k/month (−6%), $10k/month (−12%), and $30k/month (−18%). No sales call required to unlock them, no quarterly reviews to maintain them.
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