The Central Local Node (CLN)

Arbinet’s CLN is a Unix-based industrial PC platform for enhanced services which utilizes standard, ISO 9001-certified components and Arbinet’s client/server Telephony Operating System (TOS) written in C, C++ , to deliver enhanced telecommunication applications to foreign markets.

The CLN offers a standard platform on which operators of stand-alone alternate access business networks may develop an unlimited number of compatible and complementary telecommunications products and services. Arbinet’s Central Local Nodes, installed around the world, serve as gateways or points of connection into all global voice and data networks.

The CLN’s long term viability will derive from a planned transition away from routing calls through a third country (with competitive rates) to routing calls on a direct basis through a CLN-based network worldwide in conjunction with the deregulation of the foreign markets. Such structure is actually more efficient than the infrastructures of global carriers with their existing restrictive operating agreements.

The CLN is the first telco grade switch with a truly open platform utilizing components from a number of industry leading hardware developers (see CLN Hardware Specifications).

The CLN’s open architecture also features the flexibility to integrate the most prevalent existing and emerging transmission technologies and enables the speedy integration of new applications and features. Where many systems require additional hardware and in some cases separate machines when expanding applications, the CLN design allows for integrated resource sharing (i.e. ports shared by more than one application) which enables multiple applications to be layered in the same physical switch.

TOS supports Arbinet’s prepackaged telecommunications applications, while its open, versatile platform encourages Arbinet’s strategic partners to independently deploy custom applications.

CLN Benefits

Multiple Applications

The CLN simultaneously runs multiple applications on a single open platform, including Arbinet’s prepackaged application suite. Running multiple applications on a single platform enables rapid and broad market penetration. The ability to integrate multiple applications on a single platform also extends the CLNs long term viability. When one application becomes obsolete (like callback may become in a few years), another application (like international simple resale) is quickly and easily deployed in its place thus extending the platform’s life span and maximizing return on investment.

This empowers service providers entering foreign markets with unprecedented responsiveness to market demand. The CLN’s modular design and open architecture facilitates rapid development and deployment of new applications/services without major hardware changes or extended software development lead times. Implementation of new services is achieved in a matter days rather than months.

The CLN not only locally runs prepackaged telecommunications services but its open and versatile platform allows for the development of custom applications.

Simple Resale
Tandem Switching
Callback and Call-through
Voice Messaging
Voice Over IP
Debit Card / Calling Card
Fax Broadcasting
Fax Store and Forward
Message Store and Forward
Conference Calling
Voice Mail

Large Switch / High Call Volume

High switching capacity is obtained through networked distributed switching. Locally, CLNs share data over a TCP/IP backbone and voice over SC bus. Globally, CLNs share data over a number of IP compatible packet switched networks (X.25, the Internet, Frame Relay, etc.). In the near future, CLN’s will be networked over an ATM backbone. Voice and Data will be shared over ATM and distributed networked switching will achieve unlimited capacity. There is no geographical limitation to this linking. A CLN in Australia linked to a CLN in Greenland will share information as quickly and easily as if they were co-located in the same facility.


The CLN’s speed is inherent in it’s advanced components, its TOS telephony operating system, and in the underlying network on which it transmits information. The CLN’s internal components give it superior processing power — with a DSP speed of 2 Mips and an internal bus speed of 60ns, the CLN out-powers many of the large switches on the market today. TOS enables the CLN to process calls faster than any other enhanced service platform on the market by making the most efficient use of processing power. As for the underlying transmission technology, today’s most common configuration utilizes frame relay for the transmission of data and ISDN for the transmission of Voice. With ATM compatibility (25-155 Mega bits), signaling speeds will skyrocket roughly 20 times faster than SS7.

Scaleable in Size

The CLN enables low-cost market entry (with low transmission capacity) and supports rapid market penetration (with capacity added on demand). Telcos may start with smaller capacity and grow to gateway size as the market grows with no fiscal or technical penalties. The CLN is capable of efficient, flexible and rapid scaleable growth to consistently match capacity, load and functionality requirements.

Multiple Transmission Technologies

Thanks to the CLN’s SCSA compliant open architecture design and ability to incorporate hardware from a wide variety of vendors, the CLN interfaces with all existing and emerging transmission technologies. The CLN may integrate new technologies as quickly as they develop and moreover, run multiple transmission technologies on the same operating platform. Primary transmissions may be sent via the Internet, for example, with Frame Relay serving as a backup connection.

Additional Benefits

Is rapidly deployable globally: The CLN utilizes Dialogic’s internationally homologized, ISO9001 certified hardware. Benefiting from Dialogic’s international approvals in forty+ countries, CLNs are speedily deployed with a “pre-approved” status.

Supports remote system components: The CLN has the ability to separate system elements if required. With automatic call distribution or ACD, for example, customer service may be performed in one country, operator services in a another, switching in a third and billing in the fourth.

Eliminates costly system time: With negative back supervision and synch leg features, the CLN virtually eliminates costly system time. No longer do service providers have to absorb costs associated with calls that ring busy or are not answered. These cost savings may be passed along to customers in the form of lower rates.

Origination and Termination Globally: The CLN offers the ability for customers to have a call originate or terminate via any interconnected node.

Global Least Cost Routing: Each CLN chooses the origination and termination point based on the least cost route available at the time of the call.

Prevents PTT Blocking: Unique technologies of the CLN offer end-users a more reliable, continuous and improved alternate access service, particularly to those who have been affected by DID and DTMF blocking.

Eliminates System Time: The CLN alternate access network will free callback providers from absorbing the 0 to 59 second call charges commonly associated with system time. This means that costs normally associated with busy, no-answer or system time are completely eliminated. Customers will only be charged for calls actually connected. Resulting savings equal 30% of the total margin offered.

Security and Reliability: The design of Arbinet’s products and services allows for minimal system downtime, since the back-up systems temporarily route calls through alternate lines in cases of system failure.

Compliant with Most Overseas Regulations: Arbinet’s products and services operate in accordance with existing overseas telecommunications standards and regulations.

CLNTM Hardware Specifications

ISO9001 Certification

The benefits of ISO9001 certification include improved quality, consistency and customer satisfaction; increased confidence in supplier selection / capability; reduced cost of supplier components; quality system audits; strengthened competitive position; addresses quality system standardization by global customers and it provides access to European markets.

Third Party Vendors

Dialogic: various hardware and drivers
Aculab: various hardware and drivers
Ariel: various hardware and drivers
Dianatel: various hardware and drivers
Teledesign: various hardware and drivers
Intel: various hardware
SCO: Unixware Operating System
Microsoft: Windows NT
IML: ATM boards
Diversified Technologies: industrial chassis

Worldwide Approvals

With component approvals in more than 60 countries (see Component Global Approval List), new market entrants can quickly and economically enter targeted markets worldwide.

Standards Supported

CS Bus

DSP Speed

The processing speed is determined by the DSP on the Dialogic Voice Card. The current DSP speed is 2 MIPS.

CLN Hardware Description

Chassis: FTS910 19″ rack-mount chassis with dual 350W redundant AC power supplies, LED display module, (4) 5.25″ drive bays, rackslide.
Backplane: PBP-20 PCI ISA passive backplane.
Floppy drive: 1.44Mb, 3.5″ floppy drive with cable.
Hot-swap carrier: 2 removable hard drive carriers for 3.5″ wide SCSI drive (2 units).
Hard drive: 2.1 Gb fast, wide SCSI hard drive (2 units) with cable.
CPU: LBC5020 133Mhz single Pentium processor board with 512K cache, PCI local bus SVGA with 1MB, PCI IDE, advanced system monitor.
DRAM: 32 Mb DRAM (2 pieces of 16 Mb @ 60ns)
SCSI Apapter: DPT PM2044W PCI wide SCSI adapter
RAID: DPT RC4040 RAID cache module with 4Mb
PCI network adapter: SMC Etherpower 10/100 PCI network adapter
UNIXWARE: SCO Unixware 2.1. CD-Rom installed

Physical Description

Physical Weight: 60 lbs.
Physical Height: 10.5 in.
Physical Length: 19 in.
Physical Width (front to back): 24 in.
Equipment Room Footprint: Standard 9ft Rack Mount

Environment Description

Types Of Power Required: 220/110 VAC/48 VDC
Electrical Requirements: 220/110 VAC/48 VDC, 1 1/2 amps, and 300 watts
Integral UPS: External / UPS / Redundant
Environmental Requirements: 50 F to 100 F, Humidity: 10 to 85% non condensing.
Storage Environment: -40 F to 140 F, 5 to 90% humidity.
Heat Dissipation: including standby power, in British Thermal Units per hour is 4500 BTU.
Floor Load Requirements: 1,200 pounds.


T1 Capacity: 10 per chassis
E1 Capacity: 8 per chassis
Analog Line Types/ Capacity: Unlimited loop start
SCx Bus: up to 5 CLN chassis may be linked via SCx bus.
ATM Backbone: an unlimited number of CLNs may be linked via 155mg ATM switch.

Additions to the CLN do not disrupt the ongoing CLN operation since traffic can be rerouted to other nodes while upgrade is being performed.


A new CLN may be added into production in one or two days with virtually no down-time.

Servicing system components will be done by replacing components under technical support with down time to that specific CLN (the rest of the network will remain fully functional). Actual down-time varies.

Internal Redundancy

Disk Duplexing: the CLN server provides for redundancy of CLN memory. Disk duplexing is provided as an optional feature on the server.

Power Backup: The CLN uses dual power supplies that provides line filtering for each node with CLN user back up and damage prevention from power line surges due to lightning or other transient voltages or line irregularities. The CLN is properly grounded to protect against effects of ground loops, pickup noise and excessive ground current. Level of Component Redundancy: power supplies are internally redundant.

Duplex Server Drives: The CLN acts as a repository and distributor of all data (call records, billing information etc.).

Redundant RAID Drives: (Redundant Array of Inexpensive Disks). Each server has a set of redundant RAID drives. Data is written over the disk drives in a way so that if one or more of the drives goes down, data will not be lost. RAID mirrors data to an equal number of disk drives, e.g. two sets of three.

Mirroring of UNIX Server: Arbinet currently includes mirrored disk drives and dual power supplies in each CLN. Each CLN may act a server, thus by maintaining multiple nodes on the same network, each CLN may provide server redundancy.

External Redundancy

Backup CLN and Server: The best method for obtaining system level redundancy is to maintain a backup CLN on the same network. When a node or a server processor fails, the duplicated server or node takes over the existing operation. All memory and databases are resident in both units.

Backup Power: UPS: The power backup options are UPS with auto shut down if backup power is not restored within 60 minutes and with an alarm notification feature to the CLN administrator. RPS: Alternatively, the proposed backup power CLN would be capable of running full traffic through the CLN for 8 hours with the purchase of a RPS backup.


Alarm: If AC failure lasts long enough to fully discharge the backup power CLN, the CLN automatically shuts down and a page is generated to the supervisor. The alarm’s indication and monitoring capacity available for the stand-by power CLN is a visual alarm sound alarm and out-dials to a pager.

Failure of Main or Satellite Processor: Failure condition, which requires a re-load or re-boot of the CLN software, will be usually performed automatically but can also be performed via telephone, modem or directly on the CLN. The CLN re-loads automatically in 60 seconds. The failure of a server or node does not affect other nodes.

When a node or a server processor fails, the duplicated server or node takes over the existing operation. All memory and databases are resident in both units.

In the event of a processor failure, the CLN automatically switches to the standby unit without needing to reload memory.

The CLN has network supervision for all of its nodes and can perform different types of notification to support personnel.

Due to its distributed processing design, the system is able to switch from one processor to the other on a scheduled or emergency basis without adversely affecting any switch operations.

Available Alarms

Dialogic and DPT alarms are both available.

Hot Pluggable Hardware Components

The disk drives are the only hot pluggable components.

Transmission Links

Analog Lines : On CB – will allow 4 calls (TLN or REG). loss of 3 decibels on each line, therefore quality of voice is lower than a T1 interface.

T1/E1: DTMF Signaling, B8ZS, SF, Pulse on Busy, Wink Start

ISDN PRI NT: B8ZS, ESF, 64kbps signaling channel currently available. NFAS with D-channel back-up – pending Dialogic development. ATM

Data Links

Frame Relay
Private Line

Signaling Systems

Arbinet’s system currently supports:

NSI ISUP / ITU_TISUP: the CLN supports ISUP signaling but not the whole SS7 protocol. Full support of SS7 protocol depends on future Dialogic development.
PRI (NI1 / ITU-T )
R1 MF signaling
DPNSS will be supported, pending Dialogic development
C7 will be supported, pending Dialogic development

CLN Component Global Approvals

Cayman Islands
Costa Rica
Czech Republic
Dominican Republic
Hong Kong
New Zealand
Saudi Arabia
South Africa
South Korea
Sri Lanka
United Arab Emirates