IDM 120N-GP Telephone Optical Multiplexer
Standalone 120-channel FXO FXS 2.5G dual-optical-port 1+1 protection telephone E
The IDM 120N-GP telephone optical multiplexer is applied in the product showcase field, targeting industry customers' communication/transmission/dispatch equipment (to be further detailed based on documentation)
The IDM 120N-GP 2.5G dual-optical-port 120-channel telephone optical multiplexer is a PCM integrated service optical fiber transmission equipment developed by Beijing Ruiguang Jiyuan Digital Technology Co., Ltd. (Raytrans). It is used to simultaneously carry 120 FXO/FXS telephone channels, 2 independent wire-speed 1000M Ethernet channels, and 4 groups of E1 transparent transmission services over a pair of 2.5Gbps optical fiber links. As a typical multi-service optical multiplexer, this device targets high-capacity voice and data aggregation scenarios in the telephone optical multiplexer product showcase.
The device organizes narrowband voice channels and E1 channels according to the PCM30/31 format. Its optical fiber transmission channel complies with the ITU-T G.703 standard, and it provides 2 2.5G SFP optical interfaces with 1+1 protection for optical ports. The unit adopts a standard 19-inch 3U chassis architecture, making it easy to install in existing private network cabinets. It targets high-capacity voice and data aggregation nodes in electric power private networks, rail transit communication solutions, military emergency communications vehicle solutions, and government private network optical fiber communication solutions. As a professional optical multiplexer manufacturer, Raytrans integrates both gigabit network optical multiplexer capabilities and a multi-service optical multiplexer architecture in this model.
Key specifications at a glance: 2×2.5G SFP optical ports (1+1 protection for optical ports) · 120 FXO/FXS channels · 2 independent wire-speed 1000M Ethernet channels · 4 groups of E1 transparent transmission (ITU-T G.703, PCM30/31) · 19-inch 3U chassis
What is the IDM 120N-GP 2.5G dual-optical-port 120-channel telephone optical multiplexer
The IDM 120N-GP 2.5G dual-optical-port 120-channel telephone optical multiplexer is an aggregation-type device that multiplexes three types of services—telephone, E1 leased line, and gigabit Ethernet—onto a pair of optical fibers. One unit is placed at each end: one end accesses the services, and the other end restores them. All services are connected as they are according to interface-level standards, with no need to change the configuration of existing SPC switching equipment, private network terminals, or IP networks. As a multi-service optical multiplexer designed for private network scenarios, this device is positioned for high-density voice aggregation and multi-service same-fiber backhaul in the telephone optical multiplexer product showcase.
The three types of services each occupy an independent channel inside the device and do not interfere with one another. Voice is encoded into 64Kbps digital voice according to the PCM30/31 format, with each channel using ITU-T G.711 A-law compression, an audio range of 300Hz to 3400Hz, and a loop current of 25mA per channel. The 4 groups of E1 channels have a bit rate of 2048Kbps and HDB3 line coding, comply with ITU-T G.703, and are carried in transparent transmission mode without changing the time slot content. The 2 gigabit Ethernet channels are forwarded through two independent wire-speed ports after 10M/100M/1000M adaptive negotiation, providing data carrying capacity at the level of a gigabit network optical multiplexer.
How to wire 120 FXO/FXS channels
The 120 FXO/FXS channels are wired in two directions: exchange side and user side. FXO interfaces connect to exchange-side resources such as switches and SPC switching equipment, while FXS interfaces connect directly to user terminals such as telephones and fax machines. The IDM 120N-GP provides 120 standard-defined FXO/FXS interfaces in a single unit. The two interface types can be combined and configured within the same device, and the specific direction and quantity are determined by the project's voice channel requirements.
Packing 120 voice channels and optical transmission into a single 19-inch 3U device means that the line capacity that previously required multiple stacked voice devices can now be handled by one unit, with a corresponding reduction in equipment room rack space and cabling. The single-unit 120 FXO/FXS channels and 19-inch 3U architecture enable high-density voice access, which is especially direct for substations and station nodes with limited equipment room space and concentrated voice channels. It is also a common high-density access form used by optical multiplexer manufacturers in government private network optical fiber communication solutions.
2.5G SFP dual optical ports with 1+1 protection and 2 independent wire-speed gigabit Ethernet channels
The IDM 120N-GP provides 2 2.5G SFP optical interfaces, namely 2.5G SFP dual optical ports, and can provide 1+1 protection for optical ports: the two optical paths work as primary and backup. When the primary optical path experiences a fiber break or abnormal received optical power, services are automatically switched to the backup optical path inside the device, achieving seamless switchover on private network link failure without manual intervention at the opposite end or at service terminals.
On the data side, the device provides 2 independent wire-speed 1000M Ethernet interfaces. The two RJ45 gigabit ports each have full wire-speed forwarding capability, so they do not compete for bandwidth when carrying different services such as surveillance and office traffic. The 4 groups of E1 interfaces support transparent transmission mode and are backhauled over the same fiber as the telephone and Ethernet services. Only one pair of fiber cores is needed at the site side, making capacity expansion easier in sections where existing optical cable resources are tight.
What functions and interfaces does the IDM 120N-GP telephone optical multiplexer have
The IDM 120N-GP provides the following functions centered on high-density voice access, optical port redundancy protection, and multi-service same-fiber transmission.
| Function | Description |
|---|---|
| 19-inch 3U chassis architecture | Adopts a standard 19-inch 3U chassis structure, making it easy to install in existing private network cabinets with minimal equipment room renovation |
| 2.5G SFP dual optical ports with 1+1 protection for optical ports | Provides 2 2.5G SFP optical interfaces with 1+1 protection for optical ports; services are automatically switched to the backup optical path when the primary optical path fails |
| 120 FXO/FXS interfaces | Provides 120 standard-defined FXO/FXS interfaces; FXO connects to the exchange side and FXS connects to the telephone side, enabling high-density voice access in a single unit |
| 2 independent wire-speed 1000M Ethernet channels | Provides 2 independent wire-speed 1000M Ethernet interfaces; the two gigabit ports forward independently, so services do not compete for bandwidth |
| 4 groups of E1 interfaces with transparent transmission | Provides 4 groups of E1 interfaces with transparent transmission mode, a bit rate of 2048Kbps, and HDB3 line coding; services are transmitted as they are without changing the time slot content |
| Function control switches and alarm indication | Features comprehensive function control switches and alarm indication, facilitating on-site commissioning and fault location |
What on-site problems can 120 voice channels in a single unit and 2.5G optical port 1+1 protection solve
Capacity expansion at private network nodes often encounters three specific problems: concentrated voice channels but limited rack space, the entire section of services being affected once a link is interrupted, and telephone and data each occupying a pair of optical fibers. The three differentiated capabilities of the IDM 120N-GP address these three problems respectively, and are especially applicable in scenarios with high link reliability requirements such as rail transit communication solutions and military emergency communications vehicle solutions.
| Differentiated capability | Value to private network nodes |
|---|---|
| 120 FXO/FXS channels in a single unit, with a 19-inch 3U architecture enabling high-density voice access | One 3U device achieves the line capacity that previously required multiple stacked voice devices, with a corresponding reduction in equipment room rack space and cabling |
| 1+1 protection for 2 2.5G SFP optical ports, with seamless switchover on private network link failure | When the primary optical path experiences a fiber break or abnormal received optical power, services are automatically switched to the backup optical path without intervention at the opposite end or at service terminals |
| 4 groups of E1 transparent transmission + 2 wire-speed gigabit Ethernet channels, with multi-service same-fiber transmission | Telephone, E1 leased line, and two independent gigabit data channels are transmitted simultaneously over a pair of optical fibers without interfering with one another |
Technical specifications and interface specifications of the IDM 120N-GP telephone optical multiplexer
The following parameters cover optical interfaces, E1 interfaces, Ethernet, voice channel interfaces, and the power supply environment. They are based on IDM 120N-GP product data and are provided for reference in networking design and equipment selection. As an optical multiplexer manufacturer, Raytrans provides complete multi-service optical multiplexer specifications in its product showcase, making it easy to compare and select for government private network optical fiber communication solutions, military emergency communications vehicle solutions, and rail transit communication solutions.
| Item | Parameter/Specification | Description/Applicable Conditions |
|---|---|---|
| Optical interface type | SFP | Pluggable optical module, easy to replace by distance and to spare |
| Fiber mode | Single-mode (multimode optional) | Selected according to line distance and fiber core conditions |
| Optical fiber rate | 2.5Gbps | Shared by telephone, Ethernet, and E1 services |
| Wavelength | 1310nm/1550nm | Two wavelengths selectable |
| Transmit optical power | -1～-3dBm | Typical single-mode value; subject to actual measurement with an optical power meter |
| Receiver sensitivity | Better than -24dBm | The link loss budget can be calculated on this basis |
| Optical port configuration | 2 SFP, supporting 1+1 protection | Automatic switchover between primary and backup optical paths |
| E1 bit rate | 2048Kbps | HDB3 line coding |
| E1 standard protocol | ITU-T G.703 | Standard E1 interface specification |
| E1 impedance | 75Ω | Matches the E1 interface of the connected device |
| E1 frame structure/mode | PCM30/31 / transparent transmission | Services are transmitted as they are without changing the time slot content |
| Ethernet interface | RJ45 | 2 independent wire-speed 1000M channels |
| Ethernet transmission rate | 10M/100M/1000M | Complies with IEEE802.3, full/half duplex adaptive |
| Voice channel interface capacity | 120 FXO/FXS channels | 120 standard-defined interfaces |
| FXO/FXS audio range | 300Hz～3400Hz | Telephone voice channel bandwidth |
| FXO/FXS compression | ITU G.711 A-law | 64Kbps PCM encoding |
| FXO/FXS loop current | 25mA per channel | Feeding capability of each voice channel |
| Chassis structure | 19-inch 3U | Easy to install in a standard cabinet |
| Power supply mode | DC-48V / AC220V / dual power supply | Dual power supply access improves power supply reliability |
| Overall power consumption | ≤100W | Overall value including service cards and optical modules |
| Operating temperature | 0℃～40℃ | Equipment room environment |
| Humidity | ≤90% (non-condensing) | Upper limit of relative humidity |
Typical application scenarios
Electric power private network: same-fiber backhaul of substation dispatch telephone, E1 leased line, and in-station data
Between electric power substations and dispatch stations, dispatch telephone, automation E1 leased lines, and in-station Ethernet data usually need to be transmitted simultaneously. One IDM 120N-GP is placed at each site, combining inter-station voice channels, E1 channels, and two gigabit data channels over a pair of 2.5Gbps single-mode optical fibers, replacing stacked devices and multiple line rentals. The device provides 2 2.5G SFP optical ports with 1+1 protection for optical ports; services are automatically switched when the primary optical path is abnormal, giving better link availability.
Rail transit communication: centralized access of official telephone, E1 channels, and monitoring data at stations and depots
In rail transit communication solutions, stations, depots, and trackside sites are dispersed, and official telephone, E1 channels for signaling and ticketing systems, and monitoring data are often distributed over different cables. The IDM 120N-GP multiplexes the 120 voice channels, 4 groups of E1 transparent transmission channels, and 2 independent wire-speed 1000M Ethernet channels at the station side onto a pair of optical fibers for backhaul to the control center. The dual independent gigabit ports allow monitoring data and office services to be forwarded in isolation without competing for bandwidth, and only one pair of fiber cores is occupied between stations, making capacity expansion easier in sections where existing optical cable resources are tight.
Military/government private network: integrated access of high-capacity voice and data at remote stations
In government private network optical fiber communication solutions and military emergency communications vehicle solutions, remote stations, duty posts, and warehouse areas often have limited on-site maintenance resources and relatively standard equipment room conditions. The IDM 120N-GP supports DC-48V and AC220V dual power supply access, with overall power consumption not exceeding 100W, and can be installed in a temperature-controlled standard cabinet. The 1+1 protection for optical ports of the 2 2.5G SFP optical ports enables seamless switchover on private network link failure, and together with panel alarm indication it allows quick fault location and reduces on-site inspection workload.
Selection and Deployment Recommendations
IDM 120N-GP 2.5G dual optical port 120-channel telephone optical multiplexer is suited to private network aggregation nodes with concentrated voice channels that also require gigabit data backhaul and E1 leased-line transparent transmission. During selection, first determine the allocation of 120 FXO/FXS interfaces according to voice channel direction and quantity, then select between single-mode (multi-mode optional) and 1310nm/1550nm wavelengths according to optical fiber line conditions, and calculate the link loss budget using a transmit optical power of -1 to -3dBm and a receiver sensitivity better than -24dBm. For sites with high requirements on link continuity, the 1+1 protection for optical ports of the 2 2.5G SFP optical ports can be used to achieve seamless switchover upon failure; when site power supply conditions differ, DC-48V, AC220V, or dual power supply access can be selected according to on-site conditions. For specific configuration solutions, it is recommended to confirm with optical multiplexer manufacturers such as Raytrans based on project requirements.
