By default, every Simbase SIM sits behind a NAT gateway with a private IP. Outbound connections work; inbound connections don't. Assigning a Public IP removes the NAT for that SIM, giving it a routable, fixed public address that you (or anyone with the firewall rules to allow it) can reach from the internet.
Common reasons to assign a Public IP:
remote SSH into a router
configuring a gateway from your laptop
hosting a service on the device
running a VPN endpoint
integrating with a partner system that needs to push to the device.
| SIM profile | ICCID | APN to use with Public IP |
|---|---|---|
Black, Red, Green | 89103* | fixedip.us (US breakout) OR fixedip.eu (EU breakout) |
Blue, Yellow, Purple, Cyan | 89445* | fixedip.m2m |
Black, Red, Green
Blue, Yellow, Purple, Cyan
See Set up the Simbase APN for the full APN matrix and configuration steps.
Assign a Public IP
Sign in to dashboard.simbase.com
Open the SIM you want to give a Public IP
Click Assign Fixed IP
Choose the breakout location (For Black, Red and Green profiles only - 89103* range SIMs)
Click Activate Public IP
Provisioning typically takes up to 2 minutes. While the gateway is deploying, don't make further changes. Wait for the dashboard to show the IP as ready.
Device-side firewall: don't forget
The Public IP makes the SIM reachable. The device may still have its own firewall blocking inbound traffic. Common scenarios:
A Linux device with
iptablesdefaults that drop unsolicited inbound packetsA router (Teltonika, GL.iNet, Fritz!Box) with a WAN firewall enabled
An OS-level firewall (Windows Defender, macOS firewall) blocking the service port
If you've assigned a Public IP, opened the gateway firewall, and still can't reach the device, the device-side firewall is the next thing to check. Consult the device manufacturer's documentation.
Billing implications
Daily fee per assigned Public IP. The fee is billed regardless of SIM state. A disabled SIM with a Public IP still costs the daily Public IP fee until you release the IP.
Inbound traffic is billable. Just like outbound traffic, inbound packets that reach the device through the Public IP count toward your data usage. If someone on the internet sends a high volume of inbound traffic (legitimate or not), you'll be charged for it.
Releasing the Public IP stops the daily fee from the release date forward. See Release a Public IP below.
Release a Public IP
Open the SIM in the dashboard
Click the red → Release IP button (see screenshot below)
Confirm
After release, the SIM goes back to a NATed private IP.
Common questions
Yes. An assigned Public IP is static for the SIM. It stays the same as long as it's assigned to that SIM. Releasing and re-assigning may give you a different IP.
No, not directly. Release the IP from the source SIM, then assign a new Public IP to the destination SIM. It will likely be a different IP.
Up to 2 minutes. Don't make further changes during this window.
Check three things, in this order: the APN has been changed to the fixed-IP value for your profile, the device has been rebooted or the connection reset since the IP was assigned, and the device's own firewall allows inbound traffic on the port you're using.
Yes, in both directions, including traffic you didn't ask for. A device exposed to the public internet will attract scanning and probe traffic, and that counts toward usage. Consider a Usage Limit on SIMs with a Public IP.
A Public IP is billed for as long as it's assigned, whether the SIM is enabled or not. Disabling stops the daily SIM fee but not the IP fee. Release the IP to stop it.
Related
IP addresses, the parent article on IPv4 and subnets
Private vs public IP address, what's reachable from the internet
Network Address Translation (NAT), how one public address serves many SIMs
Set up the APN, the fixed-IP APN value for your profile
VPN, reach devices without a public IP
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