FXS S2 Module

Key Functions

• Adds 2 analog subscriber (FXS) interfaces via RJ11 connectors.
• Enables analog phones and fax machines to work with IP-based PBX systems.
• Ideal for hybrid deployments where both IP and analog devices coexist.

Compatibility

• Works with Yeastar S-Series and P-Series VoIP PBX systems (e.g., S20, S50, S100, S300, S412, P550, P560, P570).

Electrical & Telephony Specs

• Ports: 2 × RJ11 FXS
• On-hook Voltage: 48 V
• Off-hook Voltage: 11 V
• Off-hook Current: 10 mA
• Ring Voltage: 85 V @ 25 Hz
• Loop Impedance: ~2000 Ω
• Loop Current: ~20 mA
• Ring Load: 840 Ω
• Max Supported Line Length: ~1500 m
• Terminating Impedance Option: 600 Ω
• Pulse Dial Speed: 100–135 ms / 10pps
• Surge Protection: 1.5 kV (10/70 μs)
• REN Load @ 1000 m: 1 REN ≈ 7000 Ω, 3 REN ≈ 2330 Ω, 5 REN ≈ 1400 Ω

Typical Use Case

• Expanding an IP PBX with analog phone/fax support without needing external gateways.
• Useful in offices that still rely on a few analog handsets while migrating to VoIP.