How to Set Up Phone Numbers for Voice AI Agents in
Businesses lose thousands of dollars daily from missed calls and poor call routing. Modern voice AI agents can handle customer calls 24/7 - but only if you connect them properly to your phone system. Here's how to set up SIP trunking or call forwarding to route calls directly to your AI agents.
Two Connection Methods Compared
Businesses transitioning to voice AI face a critical first decision: how to connect their existing phone system to AI agents. The wrong choice can mean dropped calls, poor audio quality, or complex maintenance. The platform offers two proven methods, each with distinct advantages.
SIP trunking provides direct internet-based routing of calls to your AI agents, offering better call quality and more control. Call redirect is simpler to implement but relies on traditional forwarding. The best choice depends on your telecom provider, technical resources, and call volume needs.
Key difference: SIP trunking routes calls directly over the internet while call redirect uses traditional forwarding. SIP offers better quality at $0.015 per minute versus redirect at $0.02, but requires provider support.
SIP Trunk Setup Step-by-Step
SIP trunking delivers professional-grade call routing for businesses ready to modernize their telephony. This method connects your phone system directly to AI agents using internet protocols rather than traditional phone lines.
Step 1: Access Workspace Configuration
Navigate to your organization profile, select workspaces, and choose the specific workspace for call configuration. Most businesses start with their default Horizon workspace before creating specialized ones.
Step 2: Configure SIP Trunk
Under the call tab, select "Configure" then "Existing SIP Trunk." You'll need your phone label (e.g., "Sales Line"), country code, and full phone number. This creates the connection point between your provider and the AI platform.
Step 3: Set Up Inbound Routing
Select your region (US, Europe, or Asia) and enter the provided gateway addresses. These ensure calls route optimally through the platform's infrastructure. Your telecom provider will need these details to complete their side of the setup.
Pro tip: European businesses save 18% on SIP costs by selecting the Frankfurt gateway rather than London, due to lower regional peering fees.
Call Redirect Setup Step-by-Step
For businesses needing a simpler solution or whose providers don't support SIP, call redirect offers an effective alternative. This method forwards calls from your existing number to an AI-managed number while maintaining your familiar business number.
Step 1: Initiate Call Redirect
In your workspace call settings, choose "Configure" then "Call Redirect." Enter your phone label, country code, and existing business number. This identifies the line being forwarded to the AI system.
Step 2: Select Destination
Choose your destination region (currently US or Europe) and the platform will assign a local number. This becomes the forwarding target that preserves your caller ID and maintains local presence.
Step 3: Complete Forwarding
With your new AI number assigned, log into your phone provider's portal and set up unconditional forwarding to this number. The platform handles all subsequent call routing to your AI agents.
Important: Call redirect adds about 200ms of latency versus SIP's 80ms. For most customer service calls this difference is negligible, but may affect high-frequency trading or emergency lines.
Call Recording Storage Options
Regulated industries and quality-focused businesses need reliable call recording solutions. The platform offers two storage methods with different compliance and cost profiles.
The built-in cloud option automatically encrypts and stores recordings at $0.03 per minute with no setup required. For businesses needing full data control, self-hosted storage in Amazon S3 or Microsoft Azure keeps recordings in your own environment.
Cloud Storage Benefits
- Zero configuration - works immediately after setup
- Automatic encryption and access controls
- Pay-as-you-go pricing with no minimums
Self-Hosted Requirements
- Bucket name and region in your cloud provider
- Secure access rule with proper permissions
- External ID for platform authentication
Automatic Call Transcription
Converting call audio to searchable text transforms customer service analytics. The platform's automatic transcription creates instant records of every conversation without manual note-taking.
Transcripts appear alongside recordings in your call logs, searchable by keyword or phrase. This enables quality monitoring, trend analysis, and compliance verification without listening to hours of audio.
Accuracy rates: The transcription engine achieves 92% accuracy for clear English calls, with specialized models for legal, medical, and technical vocabulary available upon request.
Workspace Configuration
Proper workspace setup ensures calls route to the right AI agents with appropriate context. The platform organizes phone lines by workspace, allowing different departments or locations to maintain separate configurations.
From the organization menu, select workspaces to create or modify environments. Each workspace can have multiple phone lines with distinct routing rules, business hours, and agent assignments.
Best practice: Create separate workspaces for sales, support, and collections. This allows customized AI personalities, call handling rules, and reporting for each function.
Watch the Full Tutorial
See the complete phone number setup process in action, including timestamp demonstrations of SIP trunk configuration (2:15) and call redirect setup (4:40). The video also shows real examples of call recording storage options and transcription outputs.
Key Takeaways
Connecting your business phone system to AI agents unlocks 24/7 customer service without hiring additional staff. The right setup method depends on your technical capabilities and call quality requirements.
In summary: SIP trunking offers better quality and lower costs for businesses with compatible providers, while call redirect provides simpler setup. Both methods allow keeping your existing numbers while adding AI call handling, recording, and transcription capabilities.
Frequently Asked Questions
Common questions about voice AI phone setup
There are two main methods: SIP trunking and call redirect. SIP trunking connects your phone system directly over the internet using your existing SIP credentials, offering better call quality and direct routing.
Call redirect simply forwards calls from your current number to an AI-assigned number. While simpler to set up, it relies on traditional call forwarding technology rather than direct internet routing.
- SIP trunking costs $0.015 per minute versus $0.02 for redirect
- Call quality averages 4.2/5 with SIP versus 3.8/5 with redirect
- Setup time is 45 minutes for SIP versus 15 minutes for redirect
The platform currently supports Europe and the United States for both SIP trunking and call redirect methods. Asian support is in beta testing for SIP trunking with full rollout expected in Q2 .
Regional support affects both the available gateway locations for SIP trunking and the local numbers available for call redirect. Businesses should choose the region closest to their customer base for optimal call quality.
- US: 50 states + Puerto Rico
- Europe: 31 countries including UK post-Brexit
- Asia: Initial support for Singapore and Japan
Using the platform's cloud storage for call recordings costs $0.03 per minute of recorded audio, billed monthly. This includes enterprise-grade encryption, automatic retention policies, and unlimited playback.
For businesses preferring self-hosted storage, the platform supports Amazon S3 and Microsoft Azure at your standard storage rates. There's no additional platform fee beyond your cloud provider's charges for storage and data transfer.
- Cloud storage includes 90 days retention by default
- Self-hosted allows custom retention policies
- Transcripts are stored free with recordings
SIP trunk setup requires your phone label (a friendly name for identification), country code, and full phone number. You'll also need access to your telecom provider's SIP credentials and admin portal.
The inbound configuration requires selecting your region and entering the provided primary and secondary gateway addresses. These ensure optimal routing through the platform's global network of points of presence.
- SIP username and password from your provider
- Gateway addresses for your selected region
- Port numbers (typically 5060 for SIP)
The platform uses advanced speech recognition AI to convert call audio into searchable text in real-time. Transcripts appear alongside recordings in your call logs within seconds of call completion.
This technology identifies different speakers, filters background noise, and recognizes industry-specific terminology. Transcripts can be exported for analysis or integrated with CRM systems via API.
- 92% accuracy for clear English calls
- Speaker differentiation (agent vs customer)
- Keyword tagging for common phrases
Yes, both connection methods allow you to keep using your existing business number. Customers continue dialing the same number they've always used, with calls seamlessly routing to your AI agents.
With SIP trunking, your number ports directly to the platform's infrastructure. Call redirect maintains your number with your current provider while forwarding calls to the AI system. In both cases, caller ID displays your business number.
- No need to change marketing materials
- Customers see your familiar number
- Easy transition from human to AI agents
The platform currently supports Amazon S3 and Microsoft Azure for self-hosted call recording storage. Both options provide enterprise-grade reliability and security for sensitive call data.
To configure self-hosted storage, you'll need to provide your cloud provider details including storage region, bucket name, and create secure access rules with the required permissions for file uploads from the platform.
- Amazon S3: All commercial regions
- Azure Blob Storage: All global regions
- Requires PUT object permissions
GrowwStacks specializes in implementing complete voice AI solutions for businesses. Our team handles the technical setup of your SIP trunk or call forwarding configuration, ensuring optimal call quality and reliability.
We go beyond basic setup to customize AI agent behaviors, design call workflows tailored to your business processes, and integrate with your existing CRM or help desk systems. Our implementations typically reduce call handling costs by 40-60% while improving customer satisfaction scores.
- Free 30-minute consultation to assess your needs
- Complete technical implementation in 3-5 business days
- Ongoing optimization and performance monitoring
Ready to Route Your Calls to AI Agents?
Every missed call costs your business revenue and customer trust. GrowwStacks can have your AI call system live in under 72 hours, handling calls 24/7 at 40% lower cost than human-only teams.