BYOC SIP Trunks for AI Voice Agents: Twilio vs Telnyx

Bring your own carrier (BYOC) means your SIP trunk keeps carrying the calls, and the AI voice platform only answers them. You point inbound routing at the platform, give the platform credentials for outbound, and keep your carrier contract, numbers and billing. In the worked example below, one month of 600 inbound and 400 outbound minutes costs about $6.04 in Twilio usage or $3.92 in Telnyx usage, before numbers, channels, taxes and surcharges. Carrier choice moves your cost by single dollars. Setup mistakes cost you far more.

We build PulsyAI, a white-label voice platform that supports BYOC. Twilio and Telnyx both work with it, and so does any SIP-compatible carrier. This post compares the two big names on price and setup, and says where each one is the weaker pick.

Key Takeaways

• BYOC lets you keep your existing carrier, numbers, contracts and SLAs. No forced migration of phone numbers.
• Per-minute carrier cost is small next to platform and labor cost. At the listed US rates, 1,000 mixed minutes cost roughly $4 to $6 in usage.
• Fixed fees differ in shape: Twilio lists a monthly price per number, Telnyx lists monthly inbound channel fees. Compare the whole bill, not the headline rate.
• Three settings deserve a test before go-live: the trunk mode, the IP allow list and the transfer strategy.
• Test inbound, outbound and a live transfer on a spare number before you move a client's real line.

What does BYOC mean for an AI voice agent?

An AI voice agent needs a phone line to talk on. You can get that line in two ways. The platform can sell you a number and carry the calls itself. Or you can bring your own: the calls travel over a SIP trunk from a carrier you already pay, and the platform sits at the end of that trunk.

Our SIP trunk page describes BYOC as keeping your existing carrier contracts, billing and SLAs, with inbound and outbound calling over the trunk and number import from Twilio, Telnyx or another SIP carrier. One limit matters for planning: on PulsyAI, numbers bought inside the platform are inbound-only. Outbound calling needs an imported Twilio, Telnyx or SIP number.

For a VoIP provider or MSP, BYOC is usually the whole point. Your clients already have numbers with you. See our VoIP page for that use case. For a new agency with no carrier relationship, the platform's own numbers can be a faster start, and you can move to BYOC later.

When should you choose BYOC?

• You need outbound calls. That requires a carrier trunk or an imported number on PulsyAI.
• Clients keep their numbers. Porting numbers is slow and risky. Routing calls to the platform leaves the number where it is.
• You have carrier commitments. If you already pay for minutes or channels, use them.
• You want one bill for telephony. Your carrier invoice stays yours, and you rebill clients as you see fit.

Skip BYOC if you have no carrier account, no one who knows SIP, and a pilot to ship this week. Start on platform numbers, prove the use case, then migrate.

How do Twilio and Telnyx pricing compare?

Both carriers publish US Elastic SIP Trunking rates. The figures below come from each carrier's pricing page, read in October 2026. Rates change, vary by destination and volume, and exclude taxes, so check the pages before you quote a client: Twilio US SIP trunking pricing and Telnyx Elastic SIP pricing.

Telnyx's page lists its local number price separately from the rate card, so we leave it out rather than guess. Twilio prices its trunk on calls per second, with unlimited concurrency, while Telnyx lists channel fees for inbound. That difference changes what you pay when you have many numbers or many simultaneous calls.

Worked example: 1,000 minutes a month

Assume a month with 600 inbound local minutes and 400 outbound minutes to US numbers in the lower 48. The usage arithmetic is:

• Twilio inbound: 600 × $0.0034 = $2.04.
• Twilio outbound: 400 × $0.0100 = $4.00.
• Twilio usage total: $2.04 + $4.00 = $6.04.
• Telnyx inbound: 600 × $0.0032 = $1.92.
• Telnyx outbound: 400 × $0.005 = $2.00.
• Telnyx usage total: $1.92 + $2.00 = $3.92.

Now add the fixed fees we can verify. Five Twilio local numbers cost 5 × $1.15 = $5.75 a month, so Twilio comes to $6.04 + $5.75 = $11.79. On Telnyx, the first inbound channel tier is listed at $12 a month, so Telnyx comes to $3.92 + $12 = $15.92 before number fees, which we could not verify. Assuming that tier applies to your setup, the cheaper per-minute carrier is not the cheaper bill at this volume.

The lesson is the formula, not the winner: carrier cost = (inbound minutes × inbound rate) + (outbound minutes × outbound rate) + numbers + channel or feature fees. Run it with your own call mix. The totals above are examples, not quotes, and leave out taxes, carrier surcharges and call recording.

Where does the carrier cost sit next to platform cost?

On PulsyAI's White-Label plan you pay $99 a month with 1,000 minutes included, then $0.10 per minute, per our features page. The platform meters voice seconds on phone calls. On numbers you import from your own carrier, we do not add a separate telephony charge in the platform. For 1,000 minutes, the carrier usage above is $3.92 to $6.04, against $99 for the plan. Your carrier bill is real, but it is the smaller line. Your technician's hours spent on setup and debugging are the bigger one.

Where is each carrier the weaker choice?

• Twilio is the weaker pick when outbound minutes dominate and you chase the lowest listed rate. Its 48-state outbound rate is twice Telnyx's starting rate in the table above. It is the stronger pick when your team already knows its console and you want one familiar account.
• Telnyx is the weaker pick when you run a few numbers at low volume, because inbound channel fees can outweigh the per-minute savings, as the example shows. It is the stronger pick for outbound-heavy traffic.
• Your existing carrier beats both if you already hold a contract you can use. The rest of this post applies to any SIP-compatible carrier.

We cannot tell you which has better call quality or support. Neither carrier's pricing page speaks to that, and we do not have test data we can publish. Test your own routes.

How do you connect a trunk to PulsyAI?

The steps below follow our Twilio setup guide and the SIP trunk page. The shape is the same on Telnyx and other carriers. Only the screen names change.

1. Create the trunk at your carrier. In Twilio that is an Elastic SIP Trunk. Name it for the client or the use.
2. Set up termination. Choose a unique termination name, and protect it with an IP access control list.
3. Allow the platform's gateway. Copy the gateway address from the SIP Configuration page in PulsyAI and add it to the carrier's access list. Without it, the carrier can reject the platform's outbound calls.
4. Point origination at the platform. Set the origination URI to the SIP destination shown in the platform. Twilio requires the sip: prefix.
5. Attach a number. Buy one at the carrier or add one you already hold.
6. Add the trunk in PulsyAI. Under SIP Configuration, add the credentials. Pick the trunk type, set the outbound gateway by domain or IP (an A record is supported), and choose a transfer strategy.
7. Import the number. In the Numbers tab, import the number from the SIP trunk tab and select the trunk you just created. Then assign it to an agent.

Our site says routing changes take a few minutes to apply, so wait before you decide something is broken.

Which trunk mode and transfer setting should you pick?

PulsyAI lists three SIP modes: Static IP, Registration, and Registrar/SIP Client. The last one is how hosted PBX and cloud providers connect.

The transfer strategy is set per trunk. Dial is the default for new trunks. Refer uses SIP REFER, which lets the call be handed off with media renegotiated directly. Not every carrier or PBX accepts REFER, so test a live transfer to a human before go-live. If a transfer drops, try the other strategy first.

What should you test before moving a client's real line?

1. Inbound call from a mobile phone to the imported number. Confirm the agent answers and the greeting is clear.
2. Outbound call from the agent to a number you control. Confirm the caller ID shows the number you expect.
3. Live transfer to a human line, with both the Dial and Refer strategies if the first one fails.
4. Keypad input if you use the built-in IVR. Press digits during a call and check they are recognized.
5. A long call of several minutes, to catch dropped calls from timeout or NAT settings.
6. Failure path. Turn off the agent or the trunk and confirm calls fall back to a voicemail or a human, as your client agreed.

Keep the old routing written down so you can revert in minutes. Move one low-risk line first, such as an after-hours number.

What does BYOC mean for billing and plans?

Your carrier bills you for the trunk. PulsyAI bills you for the platform. If you rebill clients through Stripe Connect, the plan you build prices voice minutes, so fold the carrier cost into the monthly price. Our pricing guide shows the margin math with a worked example.

Check which PulsyAI plan includes BYOC before you promise it to a client. Our features page lists bring-your-own SIP trunk under the Enterprise tier, and our SIP trunk page says partners get their own instance and SIP trunk on the Enterprise plan, while also describing BYOC and number import more broadly. Ask us to confirm your plan in writing, as you should ask any vendor.

Where does PulsyAI fit?

PulsyAI fits agencies, MSPs and VoIP providers that want to keep their own carrier and still sell a branded AI voice agent. Start on our SIP trunk page. It fits less well if you want zero telephony setup and no SIP knowledge on your team. In that case, use platform numbers for inbound work and revisit BYOC when you need outbound or number portability.

PulsyAI publishes this post and sells an AI voice platform. Carrier prices are as of October 2026 from the carriers' own pages. Cost figures are examples on stated assumptions, not results from any customer, and nothing here is legal or financial advice.