How to Buy an AI Phone Number: A Guide to Your Options and Providers

The three main ways to get one

Most teams end up choosing between three approaches, and they are not mutually exclusive across a whole organization, just for a given phone number. The first is provisioning a new number directly through your voice AI platform. This is the fastest path: you pick a country and area code, the platform assigns you a live number in minutes, and you point your agent at it. It works well when you are launching a new campaign, a new line of business, or a number that customers have not seen before, so there is no continuity to protect. The second is porting an existing business number, the one already printed on your website, your ads, and your customers' saved contacts, over to the platform. Porting is a formal telecom process rather than an instant switch: your new provider requests the number from your current carrier, and there is typically a short window, often a few hours to a couple of days, where the number is in transition and calls need careful handling to avoid gaps. It is the right call when the number itself carries business value you cannot afford to lose. The third is bring-your-own-carrier, or BYOC, using a SIP trunk to connect telephony infrastructure you already run through providers like Twilio, Vonage, or a traditional carrier. This gives you the most control over routing, compliance, and existing integrations, but it also means you are managing the SIP configuration yourself rather than letting the platform handle number provisioning end to end.

Option A: Provisioning a new number directly

Provisioning directly is the simplest option because the platform handles the entire lifecycle of the number, purchasing it from upstream carriers, keeping it active, and billing you for it, so you never touch telecom infrastructure yourself. You typically choose a country, then a specific area code or region if local presence matters for answer rates, and the number is live almost immediately. This is the right default for a new outbound calling campaign, a new product line, a secondary support number, or any situation where you are starting from zero rather than replacing something. The tradeoff is that you are starting with a number that has no history and no existing recognition, so if your goal is to keep an established customer-facing number in place, this is not the option you want.

Option B: Porting your existing number

Porting keeps the number your customers already know while moving where it actually terminates, from your old phone system or carrier to your voice AI platform. Because it involves your current carrier releasing the number and the new one accepting it, porting behaves more like a migration project than a toggle: you submit a port request with account details from your current provider, there is a review and approval period, and then a cutover window where the number moves. During that window there is some risk of a brief service gap if the timing is not coordinated carefully, so it is worth asking any provider upfront how they handle the cutover and what happens to inbound calls during the transition. Porting also generally takes longer for toll-free numbers and for international numbers than for standard domestic local numbers, so build in extra lead time if either applies to you. The upside is real: your marketing, your signage, your saved contacts, and your call history all stay intact.

Option C: BYOC and SIP trunking

Bring-your-own-carrier means you keep your existing telephony relationship, whether that is Twilio, a regional carrier, or an on-premise PBX, and connect it to your voice AI platform through a SIP trunk rather than moving the number itself. SIP trunking is a standard way of carrying voice calls over the internet between two systems, and it lets you route calls to the AI agent while keeping your existing carrier contract, rate plan, and any custom telephony features you have already built, like specific call routing rules or compliance logging. This path makes the most sense if you already have telephony infrastructure in place and do not want to duplicate it or migrate away from it. The cost is technical: you or your telecom team need to configure the trunk correctly, matching codecs, authentication, and routing rules between your carrier and the platform, which takes more setup time than either of the other two options and usually benefits from someone with SIP experience on the project.

What to check before you choose a provider

A few practical details separate a smooth setup from a frustrating one, and they are worth confirming before you commit to a provider. First, ask exactly how porting works if you plan to move an existing number: what documentation they need, typical timelines for your number's country, and how they prevent downtime during cutover. Second, confirm country and area code coverage matches where you actually operate, since not every platform supports every region equally, and local presence can affect how likely people are to answer calls. Third, ask about the fee structure: most providers charge a monthly rental fee per number that is separate from usage or minute charges, so factor that in alongside your expected call volume. Fourth, if you need a toll-free number, confirm it is supported directly, since toll-free provisioning and porting can have different rules and timelines than standard local numbers. Finally, ask about call authentication and quality: STIR/SHAKEN is the industry standard for verifying that caller ID information has not been spoofed, and providers that properly implement it help your calls avoid being flagged as spam or blocked by carriers, which matters a lot for outbound campaigns at any real volume.

A short decision guide

If you are starting something new, a new campaign, a new location, a new product line, provision a number directly through your platform and get moving; there is no existing number to protect, so speed wins. If you have an existing number that customers already recognize and you do not want to lose it, plan a port: budget extra lead time, especially for toll-free or international numbers, and ask your provider how they manage the cutover window. If you already run telephony infrastructure, an established carrier relationship, an existing SIP setup, or specific routing and compliance logic you rely on, BYOC through a SIP trunk lets you keep that investment while adding the AI agent on top. We built Persistence to support all three paths so you are not boxed into one approach as your setup changes, whether that means provisioning a number in minutes today or porting your main line in six months.

Key takeaways

• An "AI phone number" is just a real telephone number connected to your voice AI agent, either a fresh number provisioned through your platform or an existing business line you route to it
• You have three main paths: provision a new number directly (fastest), port your existing number over (keeps continuity, more of a migration), or bring your own carrier via SIP trunk (most control, most setup)
• Before picking a provider, check porting support, country and area code coverage, monthly rental fees, toll-free availability, and STIR/SHAKEN caller ID authentication
• The right choice depends mostly on whether you already have a number worth keeping and whether you already run telephony infrastructure