> ## Documentation Index > Fetch the complete documentation index at: https://plivo.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Billing Concepts > How billing works for voice calls, SMS, MMS, and phone numbers on Plivo Frequently asked questions about how Plivo charges for voice calls, messaging, and phone numbers. *** ## How does voice call billing work? Plivo bills voice calls based on per-minute rates with billing increments that depend on the product: | Product | Billing Increment | How It Works | | - | - | - | | Voice API | 60-second (60/60) | Calls are rounded up to the next full minute. A 10-second call is billed as 1 minute. | | Zentrunk (SIP Trunking) | Varies by country | Per-second (1/1) for US routes, 60-second (60/60) for India routes. Other destinations vary — check your rate sheet for details. | **Key details:** * Billing starts when the call is answered, not when it starts ringing. * Both inbound and outbound call legs are billed separately. * Rates vary by destination country and number type. See [Voice Pricing](https://www.plivo.com/voice/pricing/) for current rates. *** ## How does SMS and MMS billing work? SMS and MMS are billed **per message segment**. **SMS segments:** * A single SMS segment can contain up to **160 characters** using GSM-7 encoding (standard Latin characters). * If your message uses **Unicode** characters (such as non-Latin scripts or special symbols), the segment limit drops to **70 characters**. * Messages longer than one segment are split into multiple segments, each billed separately. For multi-part messages, segment limits are 153 characters (GSM-7) or 67 characters (Unicode) due to concatenation headers. **MMS:** * MMS messages are billed per message, regardless of media size. * MMS is available only for US and Canadian destinations. See [SMS Pricing](https://www.plivo.com/sms/pricing/) for current per-segment rates. *** ## What are phone number charges? Plivo charges a **monthly rental fee** for each phone number on your account. * Rental is charged on a calendar-month basis starting from the date of purchase. * Rates vary by country and number type (local, toll-free, mobile, national). * Some countries may have one-time setup charges in addition to the monthly rental. * Numbers removed mid-month are billed for the full month. See [Phone Number Pricing](https://www.plivo.com/virtual-phone-numbers/pricing/) for rates by country. *** ## What is CPS and how do I increase it? **CPS (Calls Per Second)** is the maximum number of concurrent outbound call requests Plivo processes per second for your account. | Account Type | Default CPS | | - | - | | Standard | 1–2 CPS by plan and data region — see [Account and feature limits](/docs/voice/concepts/account-limits) | | Enterprise | Custom (higher limits available) | Outbound CPS is a single account-wide pool shared by Voice API and SIP Trunking. It is not allocated per product. An account with 2 outbound CPS can initiate two outbound calls per second in total, whether those calls go out over Voice API, over SIP Trunking, or a mix of both. If you need higher CPS for large-scale calling campaigns or high-volume applications, ask **Buddy**, Plivo's in-console chat agent, from the [Plivo console](https://cx.plivo.com/home) to move to an Enterprise plan with increased CPS limits. CPS limits apply to outbound call initiation only. They limit how fast you can *start* calls, not how many can be active at once. Concurrency is a separate limit — see [Account and feature limits](/docs/voice/concepts/account-limits). *** ## What do billing increments like 1/1 and 6/6 mean? These are standard telecom billing increment notations in the format **initial/subsequent**: | Increment | Meaning | | - | - | | **1/1** | Per-second billing — both the first and every subsequent second are billed individually | | **6/6** | Billed in 6-second blocks — the first 6 seconds are billed as a block, then every additional 6 seconds | | **60/60** | Per-minute billing — the first 60 seconds are billed as a block, then every additional 60 seconds | | **30/30** | Billed in 30-second pulses — the first 30 seconds are billed as a block, then every additional 30 seconds | | **30/6** | First 30 seconds billed as a block, then every additional 6 seconds | **Example with 60/60 billing:** A call lasting 61 seconds is billed as 120 seconds (2 minutes). In the US data region, Plivo Voice API uses **60/60** (per-minute) billing, and Zentrunk billing increments vary by destination — for example, **1/1** (per-second) for US routes. Check your Zentrunk rate sheet for destination-specific increments. In the India data region, Voice API and SIP Trunking calls are billed at a standard **30/30** (30-second pulse). *** ## Related Resources * [Payments](/docs/faq/billing-and-invoices/payments) * [Invoices](/docs/faq/billing-and-invoices/invoices) * [Taxes](/docs/faq/billing-and-invoices/taxes) * [Voice Pricing](https://www.plivo.com/voice/pricing/) * [SMS Pricing](https://www.plivo.com/sms/pricing/) * [Phone Number Pricing](https://www.plivo.com/virtual-phone-numbers/pricing/)