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SIP trunks explained

What a SIP trunk is, when your business might need one, and what information to gather before asking Dial Raven to set it up.

Set up by Dial Raven support Office Manager 5 minutes

A SIP trunk connects Dial Raven’s phone lines to a phone system you already own, such as a PBX in your server closet. Your existing system keeps handling extensions and menus, while Dial Raven carries the calls to and from the outside world.

Most Dial Raven customers don’t need a SIP trunk. If your team uses Dial Raven users, desk phones, and the ConnectUC app, you can skip this article.

When you might need a SIP trunk

  • You have an on-site phone system you aren’t ready to replace.
  • You use a device that needs a phone line, such as a fax server, a paging system, or a door entry system that connects over the internet.
  • You’re moving to Dial Raven in stages and need your old system to keep working for a while.

Where trunks show up in the portal

Most accounts don’t have a SIP Trunks tab in the Manager Portal. It only appears once Dial Raven has set up a trunk for you. Even then, Dial Raven creates and changes trunks for you, because the settings must match your equipment exactly.

What to send Dial Raven

Gather this information before you contact us. Your IT person or the company that installed your phone system can help.

  1. Your phone system’s make and model, such as “Avaya IP Office” or “FreePBX.”
  2. How it will connect:
    • A static (fixed) public IP address, or
    • Registration with a username and password, if your IP address changes.
  3. Call direction — Will the trunk handle incoming calls, outgoing calls, or both?
  4. How many calls at the same time you need (for example, 10 calls at once).
  5. Which phone numbers should ring the trunk.
  6. Where calls are allowed to go, such as only the US and Canada.
  7. Your 911 address for the location where the phone system is installed.
  8. A backup plan, for example, a number to forward calls to if your phone system goes offline.

How trunk connections work

There are two ways your phone system can connect:

  • Fixed (static) IP address — We recognize calls by your public IP address. This is the most reliable option. Your firewall must let call traffic in from Dial Raven, because a static trunk doesn’t keep a connection open the way a desk phone does.
  • Registration — Your phone system signs in with a username and password, much like a desk phone. Use it when your IP address can change. Registration trunks are limited to 30 calls at once.

A few more things to know:

  • Call limits are firm. Your trunk has a set number of calls that can happen at the same time (for example, 10). There’s no automatic “burst” above that number. When the limit is reached, the next call can’t connect. If you’re often near your limit, ask us to raise it.
  • Caller ID. By default, outgoing calls show your company’s main caller ID. If your phone system needs to send a different number per person or department, ask us to turn on caller ID passthrough. The numbers you send must be numbers on your Dial Raven account.
  • Recording. Calls over a trunk can be recorded, if your plan includes recording. Ask support.
  • Encryption certificates. Dial Raven doesn’t issue security certificates for your equipment. If your phone system insists on one for the trunk, turn that requirement off in its settings or ask your installer.
  • Compatibility. Most modern phone systems work well, but a few don’t. Tell us the make and model before you buy or change anything.

Send it to support@dialraven.com or call (434) 697-2836. You can also request remote help.

Heads up: A SIP trunk depends on your own equipment and internet connection. If your on-site system or internet goes down, calls can’t reach you. Ask us to turn on failover, so calls go to a backup number (like a cell phone) whenever the trunk can’t be reached.

911 on a trunk

Every 911 call from your phone system must carry a phone number that has your emergency address registered with Dial Raven.

  • On a fixed IP trunk, your phone system decides which number it sends with a 911 call. Ask your installer to set it to a number we’ve registered for that location.
  • On a registration trunk, we set the emergency number for you.

After any change, dial 933 from a phone on the system to hear the number and address on file. It’s a free test line, not an emergency call. See Emergency calling (E911).

Common questions

Can I use a SIP trunk and regular Dial Raven users at the same time?

Yes. Some numbers can ring your on-site system while others ring Dial Raven users.

How many calls can my trunk handle?

As many as your plan allows. Each simultaneous call needs one “path,” and each call uses under 100 kbps of internet bandwidth in each direction. Contact support to change the number of paths.

Who supports my on-site phone system?

Dial Raven supports the trunk connection. Your phone system’s vendor or IT provider supports the system itself.

How do I point a number at the trunk?

Once your trunk is set up, Dial Raven points the numbers you listed at it. If your account then shows a SIP Trunk option in a number’s Treatment list in Inventory, you can change it there too. Otherwise, contact support. See Phone numbers and devices in Inventory.

Last updated October 12, 2026

Still need help?

Call (434) 697-2836, email support@dialraven.com, or start a remote session.

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