How do I re-pair a DECT baby monitor bought second-hand?

Why does a used parent unit stay married to the seller's camera?

DECT (Digital Enhanced Cordless Telecommunications) monitors use a private radio link between a parent handset and a baby unit. They are not Wi-Fi cameras. The units ship pre-registered to each other. Manufacturer manuals say you do not pair again unless that link is lost — or, on a second-hand set, unless you need to overwrite the seller's registration.

The Motorola MBP33S user guide filed with the FCC states that a camera can be registered to only one parent unit at a time, and that pairing the same baby unit again overwrites the old registration. If you bought the screen and the seller kept a spare camera — or the other way round — the leftover half is still bound to a unit you do not have.

Which? (page checked July 2026) treats second-hand smart / Wi-Fi monitors as a data-handover problem: the previous owner must delete account access. DECT sets do not use that app account, but they still need a fresh registration so you are not staring at a 'no link' beep aimed at someone else's camera.

How do I reset and re-pair both units?

The exact button names differ by brand, but the order is the same: identify the pair, power both ends, clear the old registration, then pair within the timeout. Download the PDF for your model code from the maker before you start — a VTech +/- hold is not a Motorola PAIR-under-the-camera hold.

1. 1
   Match the family, not the colour Copy the model code from the back of the parent unit and the underside of the camera. A Motorola MBP33S camera belongs with an MBP33S parent. A VTech VM-series camera belongs with its matching VM parent. Mixed brands, or a '2' extra-camera SKU forced onto an older single-cam parent, often refuse to register.
2. 2
   Power both units Plug in the original adapters if they came in the bag (same voltage and current as the label). Charge the parent battery. Pairing menus usually need the parent awake and the camera already on. If either end is dead, stop and match the PSU first.
3. 3
   Clear the seller's registration On VTech video sets the support pages describe a power-cycle reset: disconnect power, remove batteries from parent and baby unit, wait about 15 seconds, refit, then retry pairing. On Motorola MBP33S-class sets, pairing a camera onto a slot overwrites the previous registration for that camera. The NCSC's second-hand-device advice is still to factory-reset electronics you did not set up yourself before you rely on them.
4. 4
   Open the parent pair menu VTech VM346-class support: MENU/SELECT → PAIR/UNPAIR CAM → PAIR new CAM → choose an empty baby-unit slot (maximum four cameras on those sets). Motorola MBP33S guide: M → camera icon → add → choose cam 1–4 → OK so the parent starts searching (green LED flashes).
5. 5
   Press the camera PAIR control immediately VTech VM346-class: hold both + and − on the camera until the power light flashes red then green. Other VTech cameras use a PAIR hole on the underside (a pen point for about five seconds). Motorola MBP33S: hold PAIR underneath the baby unit until the parent beeps and the picture appears. Only one baby unit can be paired at a time.

If the parent shows 'pairing failed' or keeps beeping 'no link', you are either out of range, on a full camera slot, or holding a half-set. Delete the stale camera on the parent (UNPAIR / delete cam) and try one empty slot with both units in the same room.

What if I only have the camera, or only the parent unit?

An incomplete DECT set is the usual car-boot failure. Manufacturer pairing assumes both halves of the same product family are powered and in range.

After it pairs, what else should I change?

• Search the model on GOV.UK. Pairing does not check recalls. Use the OPSS list.
• Wi-Fi / Hubble add-ons: if the set also talks to an app, follow Which? and NCSC: factory-reset, new unique password, no default PIN, updates on.
• Place the camera out of reach. The Lullaby Trust tells you to keep the control unit out of the baby's reach and to follow the maker's cord distances. Mains leads should not drape into the cot.
• Range test in your house. Which? tests indoor-to-garden drop-off; a DECT 'no link' beep after pairing is often walls and distance, not a second failed marriage.

In shortPhotograph both model codes, power both ends, clear the old registration, then pair from the parent menu while you hold the camera PAIR control. A half-set or a mixed-brand bag stays a half-set.