What type of SIM do I need for my Cell unit?

Knowledge Base

What type of SIM do I need for my CELL unit?

This guide summarizes the SIM and cellular data plan requirements typically needed to bring WTI cellular-enabled hardware online.

SIM Form Factor: 2FF Plan Type: IoT/M2M Ports: 22 + 443
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Lockout / Remote Access Warning
If you are enabling firewall rules, IP restrictions, VPN, or changing cellular/APN settings, ensure you have a fallback management path (local console access, out-of-band path, or verified remote session) to avoid locking yourself out of the device.

SIM & Service Specifications

For WTI cellular-enabled hardware, the SIM should be provisioned on an IoT/M2M data plan with an APN assigned at the SIM level.

Requirement Details Why it matters
SIM Form Factor 2FF (Standard / Mini SIM) Ensures the SIM physically fits the modem’s SIM slot.
Data Plan Type IoT/M2M plan with designated APN IoT/M2M plans are designed for device connectivity and remote management use cases.
IP Addressing Static IP recommended (Dynamic supported) Static IP simplifies stable remote access; dynamic may require DDNS.
Connectivity Direction Mobile-terminated data must be enabled Needed for inbound remote access/management sessions over cellular.
Required Open Ports TCP 22 (SSH) and TCP 443 (HTTPS) Common management ports for secure CLI and web access.
SIM Card Size Differences
Visual comparison of common SIM form factors. WTI requires 2FF (Standard / Mini).
Dimensions (mm): 2FF 25×15 · 3FF 15×12 · 4FF 12.3×8.8
SIM Form Factors Not to scale in thickness; illustrates footprint and relative size. 2FF — Standard / Mini (Required) 25 × 15 mm 3FF — Micro 15 × 12 mm 4FF — Nano 12.3 × 8.8 mm Tip: If your carrier ships a multi-size “breakout” SIM, ensure it is inserted in the 2FF configuration before installing it in the WTI device.
If you only have a Micro (3FF) or Nano (4FF) SIM, request a 2FF from your carrier. Avoid adapters unless explicitly approved for your deployment, as they can cause fitment issues.
Important notes
  • Dynamic IP addresses are supported, but typically require a Dynamic DNS (DDNS) service for consistent remote access.
  • A carrier-hosted private VPN solution can improve security, but is generally optional depending on your deployment model.
  • The APN can be entered manually during setup on the WTI device.
APN entry location (typical)
/CELL command menu → Cell Modem Configuration (enter APN and any carrier-provided credentials if required).
Carrier checklist (what to request)
2FF SIM IoT/M2M data plan APN name Static IP (preferred) Mobile-terminated data enabled Inbound TCP 22 / 443 allowed

Setup checklist

Quick steps (recommended sequence)
  1. Confirm SIM type: 2FF (standard/mini) IoT/M2M SIM.
  2. Confirm plan features: APN assigned, mobile-terminated data enabled, static IP if available.
  3. Insert SIM (power down first if required by your hardware guide), then boot the unit.
  4. Enter APN settings under the /CELL configuration menu (or equivalent UI).
  5. Validate connectivity: confirm registration and data session, then test access (SSH/HTTPS).
  6. Harden access: restrict management to approved source IPs, enable VPN if applicable, and confirm you have a recovery path.

FAQ

Can I use a consumer phone SIM?
Generally, no. WTI cellular-enabled units are best supported with an IoT/M2M data plan designed for device connectivity and remote management.
Do I need a static IP?
It is recommended for stable inbound access, but dynamic IP can work if you use a DDNS service and your carrier supports inbound connectivity requirements.
What ports should be open?
Commonly TCP 22 (SSH) and TCP 443 (HTTPS) for secure remote management.
Where do I enter the APN?
Typically under the device’s cellular configuration menu (for example: /CELL → Cell Modem Configuration).
Note: WTI devices can auto-populate the APN via OTA transfer for AT&T and Verizon. T-Mobile is not currently supported at this time.

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