The core of the RFCS system is built around a Cisco router (C8300) and contains a network interface module for analog, FXS, FXO or BRI connections as well as a service module where the XOP Linux-based software resides. This hardware and software supports analog, IP, or a combination of both types of phones, along with loop extenders. The RFCS has the ability to connect to a SIP trunk to connect off-net users. Redundant systems are often deployed for high availability, where a secondary RFCS will activate when the primary fails.

To ensure high availability, XOP Networks often deploys redundant RFCS systems. In a redundant configuration, a primary and secondary server located in different physical locations are connected, usually with a fiber optic cable. If the primary system fails due to network, power, or other issues, the connected phones automatically re-home to the secondary system, maintaining seamless functionality without interruption. All user functionality and configuration is exactly the same between primary and secondary.

The RFCS offers a web-based administration portal for system configuration, management, and monitoring. This includes:

RealView: A screen showing the status of all phones in the system, including on/off hook status and caller ID. The screen will indicate who is speaking in a conference.
Network Settings: Configuration of network parameters, email relay servers, time zones, and NTP servers.
System Settings: Adjusting system parameters, including software updates, logging, and user authentication.
Circuit Groups: Defining external network connections such as TDM, SIP trunks, and SIP extensions.
Service Selection: Implementing rules to automatically invoke services based on incoming call source/destination numbers.
Diagnostics and Backups: Tools to generate diagnostic files, create database backups, and restore from backups.
Licensing: A section to view current licenses, upload new license files, and display the system hardware address required for licensing.
SNMP: Using Simple Network Management Protocol to monitor system health such as CPU, memory, and hard drive utilization.
LDAP Directory: Integration with corporate directory servers for remote authentication and user/group importing.
Enhanced Security: Providing intrusion prevention features such as password policies, IP freezing on login failures, and X-Option sessions.

The sources provide information about T1 and E1 in the context of network interface modules for the XOP Networks system.

T1 is mentioned as a type of circuit group, which allows the system to connect to external networks for inbound and outbound calls. The system allows for four types of circuit groups: TDM, SIP trunk, SIP extensions, and attached users. The parameters that need to be set depend on the type of circuit group.
E1 is mentioned alongside T1 as part of the network interface modules in the Cisco 4000 router. The network interface modules allow for analog connections such as FXS, FXG, BRI, and also digital connections like T1 and E1.
These network interface modules are part of the core system. The system is based on a Cisco router, which includes two modules: the network interface modules and a service module. The service module is where the XOP software resides.

T1 and E1 refer to telephone trunks that carry digitized voice in Time Domain Multiplexed (TDM) channels. T1 based interfaces are pre-dominantly used in USA. Each T1 has 24 voice ports.

E1 based interfaces are pre-dominantly used in Europe, Asia and Latin America. Each E1 has 30 voice ports.

One voice port equates to one phone call.