Key Specifications & Features

From the manufacturer-documentation for the GXW4500 Series (which includes the “4‐span” model):

• It supports 4 software-configurable E1/T1/J1 spans (that is, up to 4 digital trunk ports) as part of the series. Grandstream+1

• Concurrent call capacity: Up to ~120 simultaneous calls (for the 4-span model) per the series overview. Grandstream+1

• The series supports digital signalling standards: PRI, SS7, MFC R2 on the E1/T1 side. Grandstream+1

• Dual Gigabit auto-sensing RJ-45 network ports (WAN + LAN or switched) with integrated NAT/router functionality. Grandstream

• Voice/fax features: Wide codec support (e.g., G.711, G.722, G.729, iLBC), T.38 Fax over IP support. Grandstream+1

• Security: TLS and SRTP encryption for calls/accounts. Grandstream

⚠️ Important Considerations & What to Verify

Since you are based in Bengaluru, India, and likely integrating with telecom infrastructure, here are things you should verify:

• Trunk compatibility: For India, E1 trunks are common (2.048 Mbps, 120 Ω, G.703 framing, HDB3 line code). Ensure the GXW4504 supports the exact line code, framing and impedance used by your telecom provider.

• Signalling standard: Confirm the signalling your trunk uses (ISDN PRI, CAS, etc) and verify that the gateway supports that standard.

• Call capacity vs your need: Up to ~120 simultaneous calls is the headline for the 4-span model, but check your actual usage (voice + fax + peak load) to ensure you are not undersizing.

• Integration with IP PBX / SIP trunk: Ensure your SIP trunk or IP PBX supports required codecs and DTMF modes, and that your network has sufficient QoS, low latency/jitter.

• Installation environment: Ensure you have adequate rack space, proper ventilation, stable power supply (100-240V AC as applicable), cabling for multiple digital spans and network.

• Support & firmware: Check that Grandstream (or authorised distributor) has local support in India, that firmware updates are available, and that parts/spares are accessible.

• Future proofing: If you anticipate further growth beyond 4 spans (or full move to SIP trunks), consider what your next step would be — either higher spans or full VoIP migration.