Why SIM Type Matters

Mobile network architecture has evolved. IP addressing and access control now form part of your security posture. The choice between public, private, and dynamic IP SIMs determines how your devices communicate and how protected they are.

Consumer SIMs are designed for phones — optimized for outbound traffic such as browsing and streaming. IoT SIMs are engineered for machine-to-cloud communication, with occasional inbound management. Using the wrong SIM can result in blocked access, CGNAT restrictions, or exposure to the public internet without adequate safeguards.

Public IP SIMs – Legacy Approach

Historically, assigning a public IP to each router simplified remote access. Today, this practice introduces significant risk. Public IP addresses are continuously scanned by automated bots, exposing devices to credential attacks and exploitation.

Proroute routers include integrated firewalls, NAT, and VPN capabilities. However, relying on these alone is not best practice. If public IP SIMs are unavoidable for legacy systems:

• Restrict inbound access to VPN or whitelisted IPs.
• Disable web administration over WAN.
• Keep firmware signed and updated.
• Monitor logs and block repeated attempts.

Public IP is not inherently insecure, but it represents a high-maintenance attack surface. For new deployments, private IP is the recommended standard.

Private IP SIMs – The Modern Standard

Private IP SIMs are now the industry default for IoT and industrial networks. Devices connect via a managed APN within a secure core network, eliminating direct exposure to the public internet. Traffic flows outbound through controlled gateways into your cloud or VPN endpoint.

Benefits of private IP SIMs with Proroute routers:

• No public internet visibility.
• Consistent private addressing for monitoring.
• Secure VPN or RMS tunnel for remote access.
• Full compliance with centralized security policies.

This approach aligns with Proroute’s design philosophy: edge devices operate securely within private networks, not as exposed endpoints.

Dynamic IP SIMs – Practical for IoT

Dynamic IP SIMs provide a cost-effective solution for many IoT applications. Each session uses a new IP, preventing inbound connections while supporting outbound traffic for telemetry, cloud APIs, or VPN-initiated links. Combined with Proroute’s VPN capabilities, this option simplifies infrastructure and enhances security.

Security Best Practices

Modern IoT security requires:

• Outbound-only connectivity as standard.
• Centralized VPN hubs for management.
• Encrypted tunnels between device and cloud.
• Certificate-based authentication.
• Continuous monitoring and logging.

Proroute routers support these requirements natively. The critical variable is the SIM card — and correct configuration is essential.

Trusted Connectivity from Millbeck

Millbeck is a leading UK provider of industrial IoT connectivity solutions. With extensive experience in Proroute hardware, Millbeck delivers SIMs and APN configurations optimized for secure, high-availability deployments across energy, security, and infrastructure sectors.

Available options include:

• Private IP SIMs for managed VPN connectivity.
• Dynamic IP SIMs for secure outbound-only devices.
• Multi-network roaming SIMs for coverage resilience.
• Specialist data plans for mission-critical applications.

Millbeck treats IoT connectivity as infrastructure, not a commodity — ensuring every SIM recommendation is backed by technical expertise.