Voice calls are still one of the most direct ways to communicate, but poor call quality, unclear routing, and unreliable infrastructure quickly erode trust. Best practices for voice calls focus on clarity, reliability, and designing call flows that respect the caller’s time. This article outlines practical voice call best practices, from call quality and routing to scalability and user experience, for teams building or operating modern voice systems.
SignalWire best practices for voice calls
As voice communication continues to evolve, ensuring your calls are delivered reliably, securely, and with full compliance is more important than ever. SignalWire empowers developers and businesses to build advanced voice applications with a foundation of trust and control.
This guide outlines the best practices for optimizing outbound and inbound voice communication on SignalWire, from caller ID reputation to security, compliance, and performance monitoring. Following these practices will help ensure your calls are not only successful, but also legal, trusted, and future-proof.
SignalWire legal overview
The SignalWire Cloud Agreement governs your use of SignalWire’s cloud-based communication platform, including its voice, messaging, video, and AI services. This agreement outlines the legal terms between you (the customer) and SignalWire, Inc., and ensures that both parties understand their rights, responsibilities, and obligations when using the platform.
View the SignalWire Legal Documents page to familiarize yourself with all of SignalWire’s policies.
Voice calls: Getting started
- Follow our “Making and Receiving Phone Calls” guide to make and receive your first phone calls using SignalWire Markup Language (SWML) and the SignalWire REST API.
- Review the Voice Prerequisites to be able to make calls with SignalWire.
- SIP is the signaling protocol SignalWire uses to transmit calls through the cloud, enabling VoIP and eliminating the need for physical phone lines. Learn more with our “Get Started with SIP” guide.
- Follow expected throughput norms to avoid throttling and carrier filtering. SignalWire enforces 1 call per second per number with configurable limits.We do have offerings available for high throughput toll-free calling and high throughput SIP calling. Please reach out to Support@signalwire.com to get this process started.
Build trust and reputation with PSTN
To ensure your voice calls reach consumers and aren’t filtered, blocked, or marked as spam, you must establish trust with carriers and receive endpoints. The core concepts apply regardless of provider.
Use verified caller ID & CNAM
Register your caller identity (CNAM) with carriers and ensure numbers are correctly provisioned. SignalWire supports PSTN connectivity with verified phone numbers.
When placing repeated calls to the same contacts, use the same validated number with clear CNAM branding.
Monitor reputation & spam labeling
SignalWire Status Callbacks let you build analytics and track call progress and errors programmatically.
Implement logging and status callbacks to monitor call outcomes (e.g., failures, blocks, quality). Use these metrics to adapt dial plans and reduce harmful routing patterns.
International calling and usage
When placing international calls through SignalWire, it’s important to understand the regulatory landscape in both your own jurisdiction and that of your end users. Each country governs its telecommunications infrastructure independently, which can lead to important differences in call handling, number formatting, dialing behavior, and content restrictions.
SignalWire’s global voice platform is designed to work across borders, but regional nuances—such as how calls are routed, answered, or even filtered—can vary significantly between countries and carriers.
Best practices for international usage
Review local telecom laws: Before launching services, verify that your use case complies with the voice and data regulations in the destination country.
Use properly formatted E.164 numbers: Ensure international numbers are dialed in full international format to maximize routing compatibility.
Be aware of call behavior differences: Some countries may introduce ringback tones, in-country announcements, or network-based call filtering.
Expect evolving regulations: Carrier requirements and enforcement policies can change quickly, particularly regarding spam prevention, lawful intercept, or caller ID presentation.
Learn more about International Support with SignalWire.
Toll-free phone number restrictions and limitations
Toll‑Free phone numbers are primarily intended for domestic inbound voice communications, with routing and billing models built around the expectation that the calling party—not the business—pays for the call. Because of this, carriers often apply unique technical and policy requirements to Toll‑Free numbers.
When using SignalWire toll‑free numbers:
Inbound domestic calls are fully supported and are the intended use case.
Outbound calling from toll‑free numbers may fail, as many carriers do not support or expect toll‑free numbers to be used as the caller ID for outbound PSTN calls.
Caller ID presentation on outbound toll‑free calls is not guaranteed and may be blocked or rejected by downstream networks.
To maximize deliverability and reliability:
Use Toll‑Free numbers for customer support lines, hotlines, and inbound IVR/AI agent workflows.
For outbound PSTN voice calls, we recommend using a standard long code or other supported domestic number types that align with carrier expectations.
Always ensure numbers are dialed in E.164 format for global compatibility.
Voice call troubleshooting
Secure your communications and credentials
Protect your infrastructure, caller data, and platform integrity. Visit the SignalWIre Trust Center to learn more about our infrastructure.
Protect API keys and account access
Store API tokens securely, avoid embedding them in public source code, and rotate them regularly. Use strong authentication, including MFA on your SignalWire account.
Encrypt SIP control and media
When using SIP trunks or custom SIP endpoints on SignalWire, prefer TLS/SRTP to secure call setup and audio RTP.
Enforce least‑privilege access
Limit API scopes and user permissions within your Space to only what each service needs. Regularly audit user roles and deactivate abandoned credentials.
Compliance & data protection
Adopt safe practices in your application logic for compliant communication. Visit the SignalWire Compliance Center to view all our certifications.
Compliance with regulatory frameworks
SignalWire Certifications:
SOC II Type II, HIPAA, GDPR, CCPA, PCI DSS, ISO/IEC 27001:2022
SignalWire offers Business Associate Agreements (BAAs) for those working within regulated industries.
Secure handling of sensitive data
Avoid passing sensitive customer info (like PII or payment details) through unprotected channels. If you collect credit card or sensitive personal information during calls, segment workflows so that AI or third‑party systems never see raw data.
(Example best practices are shown in SignalWire’s AI payment processing guide.)
SignalWire suggests to follow the Telephone Consumer Protection Act (TCPA), all applicable FCC orders, and Robocall Mitigation Database to stay up to date with industry standards.
Frequently asked questions
What are the most important best practices for voice calls?
Best practices for voice calls include maintaining high call quality, minimizing latency, designing clear call flows, and ensuring calls are routed reliably and efficiently.
Why does call quality matter so much for voice communication?
Poor call quality creates frustration and reduces trust. Clear audio, low latency, and reliable connections are essential for productive conversations and positive user experiences.
How should voice call flows be designed?
Voice call flows should be simple, predictable, and focused on helping callers reach the right destination quickly without unnecessary prompts or delays.
What role does scalability play in voice call reliability?
As call volume grows, voice systems must scale without introducing dropped calls, delays, or inconsistent behavior. Scalable infrastructure helps maintain reliability during peak usage.
Are voice calls still relevant in modern communication systems?
Yes. Voice calls remain critical for real-time conversations, urgent communication, and situations where clarity and immediacy matter more than asynchronous messaging.
