Expert View

November 8, 2005
The MX25 SIP Gateway: Perfect for the SMB

BANGALORE -- Though the technical journals have been talking about it for several years now, VoIP is finally achieving critical mass. In fact, most industry analysts are now calling 2006 “the year of VoIP.” Sales of traditional TDM equipment are dropping off rapidly. In fact, some analysts predict sales of IP telephony equipment will overtake TDM sales within the next two or three years.

Zultys Technologies,a premier manufacturer of communications equipment for businesses and enterprises, has produced some of the most innovative designs that integrate functionality while interoperating with industry standard devices. Its award winning products have provided the market with solutions that increase worker productivity and scale for future growth.

Highly regarded by analysts, press, channel partners and customers, Zultys is recognised for its refreshing approach to VoIP and convergence. Zultys has a clear strategy of product introductions for convergence of voice, data, video, and fax. By heavily investing in research and development, Zultys responds to evolving requirements and brings cutting-edge solutions into the market, much faster than its competitors. Zultys introduces a new product every month. All products complement one another, to enable improvement in productivity and to provide seamless connectivity to all its users, regardless of their location.

Convergence Plus recently spoke with M G Kabir, country manager for India & SAARC, to know more about the cost effective way the company build corporate networks on the ISP / WAN backbone using the MX25 SIP Gateway.

Excerpts from the interview:

Convergence Plus: What is worldwide product offering from Zultys in the VoIP Gateway Segment?

MG Kabir: Zultys’ flagship product is the MX250 Enterprise Media Exchange. The MX250 is a powerful IP PBX that converges data, voice, video and fax—all in a single appliance. The MX250 supports 5 to 250 users in a single box and combines the features of an Internet gateway (switch and router), PBX (line interface, analog circuits, auto attendant, voice mail, and ACD) and adds support for video calls.

However, the MX250 may be overkill for many smaller businesses or branch offices. That’s why the MX25 was created. The MX25 extends the functions of the MX250 to offices where there are 25 or fewer users. The MX25 also acts as a SIP gateway, either as a stand-alone product or a back up, like when the WAN link to the main office fails.

CP: How is the MX25 used in a small branch office?

MGK: Used in conjunction with the MX250, the MX25 provides a low cost solution giving full functionality of MX250 to a branch office, while ensuring that standard telephone access is always available at that office. Users at that remote site get complete access to voicemail, automated attendants, presence and instant messaging. These users can communicate with people anywhere else in the enterprise in the same manner as if in the main office and can serve as operators or agents of ACD groups.

CP: How is it used as a SIP gateway?

MGK: As a SIP gateway, the MX25 converts speech traffic on an Ethernet circuit to a TDM network interface. The MX25 supports 30 channels of speech traffic and has three slots that can accommodate analog FXS, analog FXO, ISDN BRA, T1, or E1 interfaces. These are the same interface cards as used on the MX250 and provide complete modularity.

By using the MX25 in a LAN alongside an MX250, users can increase the number of analog extensions to add analog phones, DECT phones, credit card machines, modems, overhead paging systems, and fax machines.

CP: How is the MX25 provisioned and configured?

MGK: Since the MX25 is managed through the same Admin UI as is used for the MX250, it becomes an integrated part of a company’s communications solution. This graphical user interface provides a single point of administration for system configuration, viewing of status, troubleshooting, and problem resolution. When used as a stand-alone gateway, this user interface provides rapid configuration and diagnostics.

CP: What are the key features of the MX25 SIP Gateway?

MGK: Key features of MX25 SIP Gateway are s tandalone SIP gateway, remote survivability functions, 30 channels of speech traffic to TDM, modular installation of telephony circuits, 8 to 24 analog FXO and FXS circuits, 1 T1 circuit (CAS or ISDN), 1 E1 circuit (ISDN), 4 to 12 ISDN BRI circuits (S/T), flexible dial plan, interoperates with any standards based network infrastructure and based on highly stable embedded Linux operating system.

CP: How does the MX25 really work?

MGK: The MX25 is a modular device that is a stand alone SIP to TDM gateway. It converts the format of a phone call to allow it to pass between the IP network and the public telephone network. The MX25 connects to the TDM using analog, T1, E1, or Basic Rate ISDN. Even when there is a failure in the WAN link connecting the MX250 and the MX25, the MX25 continues to operate and allows for incoming and outgoing calls to the TDM.

There are three slots in the MX25, which allow for the insertion of plug-in modules. These modules provide connections to devices such as phones and fax machines, and connection to the TDM. For connecting to analog phones and fax machines, an FXS module is used. For connecting to the TDM using analog, an FXO module is used. For connecting to the TDM using ISDN BRA, a BRI S/T module is used. An MX25 can accommodate any combination of these cards. For connecting to the TDM using T1 or E1, a T1/E1 module is provided. Only one of these cards can be inserted into an MX25 and only one T1 or E1 circuit can be used.

CP: What are the different modes in which MX25 can work?

MGK: In normal operation, the IP phones located at the branch office register with the MX250 at the main site. The phones consider the MX250 their primary SIP server. The IP phones also register with the MX25 and consider it their backup SIP server. This provides a level of redundancy when communication with the primary SIP server is not possible.

The MX25 sends a registration to the MX250 for each analog phone, fax machine, or credit card reader configured on an analog FXS module. This is how the MX250 knows how to route an incoming call on one of its interfaces to an analog extension on the MX25. When there is an incoming call from the TDM on the MX25, the call is redirected over the IP network to the MX250. The MX250 decides where to route the call. When an outgoing call is made using any IP phone, the call setup is performed by the MX250. The dial plan on the MX250 is configured by the administrator to provide a least cost routing.

CP: What happens to the MX25 when the WAN link fails?

MGK: The MX25 supports a dial plan that is configured by the administrator to provide intelligent call routing to any of its configured TDM interface groups. When the WAN link fails and the IP phones can no longer communicate with the MX250, they automatically attempt to make calls through the MX25 (backup SIP server). Because of this, outgoing calls from the IP phones are routed locally to the TDM through the MX25. The administrator can configure the MX25 to route all incoming calls from the TDM to specific devices.

When the WAN connection is restored, communication with the MX250 resumes and normal operation is automatically restored. No intervention is required from the administrator.

CP: What are the benefits of a SIP gateway like the MX25?

MGK: The MX25 can provide the functionality of a modular SIP gateway, which is beneficial for a host of applications for the enterprise. Its dial plan allows for routing among multiple SIP servers (internal or external) as well as telephony circuits, which makes it functional within almost every VoIP application.

Flexible Dial Plan:

The following connectivity diagrams do a better job of explaining how the MX25 connects to other network devices.

A. Connecting analog devices to a SIP network


B. Connecting a SIP network to the TDM


C. Connecting a SIP network to both TDM and analog devices


D. Connecting telephony system to a SIP network


E. Connecting two telephony systems together using SIP

CP: What are the data network features and capacities of the MX25?

MGK: The MX25 provides a single 10/100Base-T circuit that connects to an external Ethernet switch. The Ethernet port can be configured to support IEEE 802.1q VLANs and IEEE 802.1p quality of service at the Ethernet layer. For quality of service at the IP layer, Differentiated Services is supported.

The analog FXS and FXO are octal modules and the BRA is a quad module, supporting 4 (2B+D) circuits. The T1/E1 module provides two physical circuits; however, only one circuit can be used in an MX25 (both circuits can be used when the module is purchased for an MX250). Any combination of modules can be used, but only a maximum of 30 concurrent voice channels to the TDM is supported. The MX25 can learn the information of up to 25 users from an MX250. It can accommodate up to 100 simultaneous SIP registrations.

CP: Is the MX25 difficult to manage and does it operate on standard power output??

MGK: The MX25 is administered using a single graphical user interface that runs under Windows 2000 or Windows XP. This interface provides the administrator with a powerful tool that allows for configuration, maintenance, and troubleshooting. When used in conjunction with an MX250, the configuration information can be automatically sent to the MX25.

The MX25 derives its power from ac. The universal ac input operates from 90 V ac to 240 V ac, 47Hz to 60Hz. The maximum power drawn by the MX25 is 19 W. The MX25 has an analog port that is marked as a system failure transfer (SFT) port. This is a special port that directly connects to the first analog FXO circuit when power is lost and there is an analog FXO module in slot 1. This allows for a direct connection to the central office so dial tone can be received and calls can be made.

CP: What are the technical specifications of the MX25?

MGK: The MX25 uses custom hardware that incorporates all of the processing power and resources required to scale from 1 to 25 users. It is 100 percent based on open standards, utilising a real time Linux operating system and SIP for call control. This ensures interoperability, security, and high quality voice. The modular design allows for flexibility of configuration and provides room for future growth.

Operating temperature: 10°C to 40°C (50°F to 104°F)
Weight: 2.27 kg (5 lb)
Size: 270 mm (W) x 210 mm (D) x 85 mm (H) (11” x 8” x 3”)
Mount: Standard 19" rack from front, mid, or rear; 2 RU (89 mm)
Safety: UL 60950, CSA-C22.2, EN 60950:2001
EMI: FCC Part 15, ICES-003 class A, CISPR 22, AS/NZS 3548 Class A
EMC: CISPR 24 (EN55024:1998), EN61000-4 

CP: Which market segment you are trying to address worldwide?

MGK: The MX25 is an ideal solution for building a corporate network on ISP Backbone. Using the MX25 organizations can integrate existing PBXs in different locations. All MX25s in different geographical locations can work with a centralized IP PBX (the MX250) located in the main office. This integrates the existing PBX on the WAN network for the exchange of voice and data. All PBXs at different branch and remote locations can communicate with the central IP PBX and share telephony features. This is not available in conventional gateways on the market today. This provides tremendous value add and ROI for any corporate network. It also offers a common management platform for all gateways integrated with the MX250 IP PBX at the main office.

A second, and perhaps larger, area of deployment is in the BPO and call center industry. Target customers are those who want to integrate with ITSPs for cost effective voice minutes. The MX25 offers seamless integration with ITSP’s and also offers a dial plan that can support multiple ITSP’s at the same time. The MX250 is a cost effective solution providing remote telephony at small offices and a SIP gateway to connect to the TDM network.

Contact:
Zultys
www.zultys.com