Factory reset guide for old business desk phones (2026)

Why this matters

Old desk phones hold more data than most people expect. Local phonebooks with 200+ contacts, call logs, speed-dial labels, and on IP handsets the SIP credentials and provisioning server URLs. If you're moving those handsets on — to a reseller, a charity, a skip, or a shredder — you want the data cleared first.

This guide walks through the factory reset process for the common Avaya business desk phones you'll find in UK SMEs, and points to the manufacturer documentation for other common brands. It's honest about where reset isn't possible, and what to do in that case.

Jump to your model

• Avaya digital: 1408, 1416, 9504, 9508
• Avaya H.323 IP: 9608, 9611G, 9621G, 9641G
• Avaya SIP: J139, J159, J169, J179, J189
• Cisco, Mitel, Poly, Yealink
• What resets clear and what they leave behind
• If reset isn't possible: destruction and audit trail

Avaya digital: 1408, 1416, 9504, 9508

These are the black-and-white handsets you see on secretary desks, reception counters, and shop-floor phones across UK SMEs. They connect to an Avaya IP Office (or older Definity) PBX via a two-wire DCP line and draw power directly from that PBX port.

The reset itself

1. Make sure the handset is plugged into a working DCP port on the PBX and the display has finished booting.
2. Press the Menu key (or the A key on some SKUs).
3. Navigate to Phone Settings, then Erase, then All (the exact wording varies slightly across firmware revisions).
4. Confirm the erase.
5. The phone clears the local personal directory, the call log, redial history, and the line-key text labels.

The catch

There's no CRAFT code or hidden menu that works standalone on a digital handset. The phone will not boot without DCP line power from an Avaya PBX, so if your PBX has already been decommissioned, or you never had one, you cannot reset these handsets yourself.

Your options in that case:

• Destroy the PCBs yourself. A cordless drill through the memory chip area takes about 30 seconds per unit. Photograph before and after against a numbered serial log. This aligns with the NIST 800-88 "Destroy" category and gives you a defensible audit trail. Free, if you already own a drill.
• Send them to us. We keep an Avaya IP Office in-house so we can power each unit up on a DCP port and run the reset properly. Comes with a Certificate of Sanitisation. Works at any lot size.
• Book a certified WEEE destruction contractor. For very large volumes (hundreds of units) or if you specifically need on-site shredding, commercial WEEE destruction firms (Shred Station, Restore Datashred and others) offer paid on-site or collection services with certificates. Priced by weight or volume, usually a minimum call-out charge that only makes sense at scale.

Avaya H.323 IP: 9608, 9611G, 9621G, 9641G

The colour-screen IP phones you see on fee-earner desks. Ethernet connection, PoE-powered.

The reset

1. With the phone idle (registered or unregistered, either works), press Mute.
2. Dial 27238# on the keypad. That's C-R-A-F-T. A hidden Craft menu appears.
3. Scroll to Clear, press Start, then confirm.
4. The display shows "Clearing Values" and the phone reboots to factory defaults.

If the phone won't reach idle (stuck on boot), power it up and press \* when the initial prompt appears, then 27238# to reach the Craft menu that way.

Important: Clear vs Reset

The Craft menu also has a Reset option. That's a soft reboot only. It does not wipe user data. Choose Clear for sanitisation, always.

What Clear removes

Local personal directory, call log, redial history, SIP and H.323 credentials, provisioning server URL, 802.1X credentials, TLS certificates if present, ringtones, and network config. The firmware stays intact.

Avaya SIP: J139, J159, J169, J179, J189

The J-series is Avaya's current SIP-native range. Reset procedure is the same as the H.323 IP models.

1. Press Mute.
2. Dial 27238#.
3. Craft menu appears. Scroll to Clear, press Start, confirm.
4. Phone clears and reboots to defaults.

Same Clear vs Reset caveat as above.

Other brands: Cisco, Mitel, Poly, Yealink

Our specialist depth is on Avaya. For other common business desk phones, the manufacturers publish their own reset procedures and we recommend using those:

• Cisco IP Phone 8800 series — Settings, Device Administration, Factory Reset. Full guide on Cisco's admin documentation.
• Mitel 6900 series — Settings, Admin, Factory Default. Admin PIN required. Mitel publish per-model guides on their support portal.
• Poly (Polycom) VVX series — during boot, hold Volume Up + Volume Down + Speaker + Mute, then enter the MAC address (uppercase, no colons) as the admin password. Poly publish the sequence in their VVX admin guide.
• Yealink T5x / T4x series — Menu, Settings, Advanced (default password 0000 or admin), Reset to Factory. Yealink publish full guides at support.yealink.com.

If you'd rather not do this yourself, we'll collect any common brand, wipe it against the manufacturer's own procedure, and issue the certificate. Case-by-case, get in touch with a rough kit list.

What resets clear and what they leave behind

Voicemail, call recordings, and system directory data are stored on the PBX server, not the handset. Resetting the handset doesn't touch them. That's a separate job — done on the PBX itself before you retire it — and it's usually a bigger data-at-rest problem than the handsets are.

If reset isn't possible: destruction and audit trail

Some situations you can't reset your way out of. The PBX has already gone. The handsets won't power on. You've got 40 units and no time. All valid.

The NIST 800-88 framework — which is the widely-accepted standard for media sanitisation — recognises three categories: Clear (software reset), Purge (cryptographic erase, beyond most business needs), and Destroy (physical). For desk phones where Clear isn't possible, Destroy is the honest fallback.

Physical destruction, done properly (free at small volumes)

• Locate the main circuit board and the memory chip on it.
• Drill a hole through the memory chip area with a 3-4mm bit, or snap the PCB in half at that point.
• Photograph each unit before and after against a numbered serial log.
• Issue a Certificate of Destruction naming the method: "PCB drilled through NVRAM area."

This is defensible for SRA compliance and lines up with NIST Destroy. It doesn't need a shredder contract or a paid disposal service.

Certified WEEE destruction (for large volumes only)

At hundreds of units or higher, commercial WEEE destruction contractors offer on-site shredding or collection with formal certification. Shred Station, Restore Datashred and similar operators cover the UK. These are paid services, usually priced by weight or volume with a minimum call-out charge, so they only make commercial sense at real scale.

If you'd rather not touch any of it

Send the lot to us. Serial logged, wiped where possible, destroyed where not, certificate at the end. That's the whole job.

Get help

If you've got desk phones to move on and want a hand with the reset or the whole collection, drop us a note through the contact page with a rough kit list.

See also: What to do with old Avaya digital phones in 2026 · Data security process · Sell your desk phones