Does Adtran Still Make Phones? A Voicemail Checklist for the 424 ONT

I've been handling fiber voice service orders for eight years. I've made, and documented, 23 mistakes that probably added up to $40,000 in wasted time and truck rolls. The most avoidable one was trying to set voicemail on the wrong device. This checklist is what I use before I touch an Adtran 424 ONT now.

It applies if you have a regular phone plugged directly into the 424 voice port, or if the 424 terminates the fiber and your phones sit behind a PBX. There are 7 steps. Do them in order. The step that surprises most people is the first one.

The first time someone asked me does Adtran still make phones, I answered yes, the 424 ONT on your wall. That was not the answer they wanted. They wanted a handset. But it is the right place to start.

The first phone to configure is not the phone. It is the line.

1. Find the actual voice port on the 424 ONT

Look at the label on the ONT. The 424 has Ethernet ports, and many variants also have POTS voice ports. The voice port is usually labeled FXS or PHONE. A normal analog telephone plugs into that port. If your install is VoIP-only, for example a separate SIP phone connected to a switch, you might not use the FXS port at all. In that case, voicemail has nothing to do with the ONT; it is handled by the PBX or the provider.

I spent a full day at one site because the installer plugged the phone into LAN port 2. It powered the phone, but there was no dial tone. That was not an Adtran problem. The FXS port was never involved.

2. Verify voicemail is provisioned before you touch the phone

This is the red flag I look for first. Voicemail is not a setting on the 424. It is a service from the voice provider. In a typical carrier-managed deployment, the ONT is provisioned using TR-069 or an OLT-side config. The local web page might show FXS settings, but if the account is not provisioned, pressing a voicemail key on any handset or dialing the access number will fail.

What I say to a customer is: please ask the provider whether voicemail is included. And ask what is NOT included. I ask the second part after a rollout where the customer assumed the free trial was permanent. It was not. The provider did nothing wrong; the contract was clear. I just did not read it.

3. Get the voicemail access number and dial plan locally

Every provider is different. The mailbox may be reached by *98, *123, or the phone's own number. Do not assume the Messages button on a cheap desk phone works. I once spent 40 minutes in a conference room because the user pressed a button with an envelope icon. The button was an unused analog phone feature. No programming, no vendor.

Program the access number into a speed-dial key if you can. That is the closest thing to a dedicated voicemail button on an analog handset.

4. Set the mailbox PIN and change it in the portal if there is one

Call the voicemail access number. The default PIN is often the last 4 digits of the telephone number or 0000. The system should force you to change it. Once changed, update the same PIN in the provider portal if one exists. Some setups push voicemail settings back out to the platform, and an old PIN in the portal can overwrite the mailbox change.

That one caught a team I worked with. They changed the PIN on the phone, but the portal still had the old PIN. The next sync reset the mailbox. The user was standing there while I lost the ability to log in. My fault. New rule: portal first, phone second.

5. Record both unavailable and busy greetings separately

This is the step almost everybody ignores. They record one greeting and assume it covers every case. In most voicemail systems, the unavailable greeting and the busy greeting are separate options in the same menu. An unanswered call after four rings uses the unavailable greeting. A call while the line is busy uses the busy greeting. If you only change one, the other still says the default.

I once tested a setup by calling when the user was unavailable. The greeting was perfect. Then I called from a second line while the user was on the phone. Default voice. My client heard it. That is the kind of embarrassment that stays with you.

6. Test from a second phone

Leave a real message. Retrieve it. Then call again while the phone is busy and leave another. Retrieve that too. That two-minute test catches more issues than any configuration review.

If the phone is on the 424 FXS port, pick a second phone that is not on the same shared line. If the second phone rings the same number, you cannot test the busy greeting. You need a separate number or a temporary mobile phone calling in. This is not a no-brainer; it is a whole troubleshooting rabbit hole I have fallen into.

7. Write the mapping down and attach it to the ONT

The box may sit in a wiring closet for years. The person who configured it will not be there forever. I keep a simple sheet on the side of the ONT: location, ONT serial, FXS port number, telephone number, voicemail access number, default PIN rules, and provider support contact. Since Q1 2024, 47 potential voicemail issues have been caught using that sheet. The number is not meant to impress you; it is meant to show what happens when a small detail is documented.

Attach the sheet with a zip tie, not tape. Tape falls off. I learned that at a site where the only record of the voicemail access number was on a sticky note under a printer. The sticky note was there. The printer was gone.

Does Adtran still make phones?

I get this question because the 424 ONT has phone ports. Adtran does not sell consumer smartphones, and as of early 2025 I am not aware of a new Adtran-branded desk handset. The 424 is not a phone. It is a network access device with a phone interface. If you need a physical device on someone's desk, an analog phone, a SIP phone, or a PBX is where that ends.

Another way to answer the question: does Adtran still make phones? The wrong question is about the handset. The right question is what is the phone line connected to. If it is connected to the 424 FXS port, voicemail is almost always on the provider side. If it is connected to an Adtran NetVanta PBX, voicemail lives on that PBX. The 424 is the door, not the voicemail system. Period.

Common mistakes I made so you do not have to

Most of the items below feel small until they are not.

• Plugging a phone into the wrong port. Check the FXS label before calling support.
• Changing the PIN on the handset but not the portal. Portal first, then phone.
• Recording one greeting. Record both, and test both.
• Forgetting to ask what's included. The price quote can look great and still not include mailbox setup.
• Trusting an envelope button on a cheap phone. Program a speed dial to the voicemail access number instead.

So here is the bottom line. If you search for how to set voicemail on an Adtran phone, the answer is not a hidden menu in the ONT. It is a provisioning question. Confirm the mailbox exists with the provider, get the voicemail access number, record both greetings, and test with a second line. The first phone to configure is not the phone. It is the line. That is the whole trick.