Introduction
In a small island nation a telecommunications public/private entity, wanted to support three call centers in the country with U.S.-native 800 number service. By using a combination of voice over IP (VOIP) and SS7 switching along with collocated hardware, the entity is able to provide up to sixty (60) telephone sessions across a megabit of long-distance bandwidth. Using traditional telephony and switched circuits with the same long-distance resources would have only provided sixteen (16) telephone circuits with much greater headaches in implementation. Using VOIP provided greater telephone capacity, much simpler and quicker implementation, and at a better cost.

The entity sought out a facility that was able to provide:

  • Colocation space
  • Telecom support services
  • SS7 switch support to originate and terminate calls in the United States

Colocation Corporation was able to provide all of these services for the customer.

From Dial Tone to Data
On the island side, telephone calls are routed and delivered through a Nortel PBX system and onto ISDN PRI lines. The PRI lines go into a Cisco Series 3660 Multiservice Platform router. An ISDN PRI card in the router converts the voice lines into voice over IP (VOIP) traffic; currently the customer can support up to 60 simultaneous phone calls on their end. Voice is compressed using the G.729 protocol.

The router takes the data traffic and sends it through the Cisco Series 3660 E1 card inside of the router and connected to a dedicated leased line to the United States.

Across The Sea
A dedicated leased line was put into place between the island nation and Coloco's facilities. The leased line, configured as a half-E1 (An E1, the inter is made up of 32 channels (phone lines) and can deliver data at up to 2 Mbps) originated at the island, went through Europe, and landed in the United States at a facility in Long Island, New York.

From Long Island, the leased line was passed to a switching center in New York and converted to a U.S. standard T1 and handed over to a U.S. carrier. The line was brought down from New York to Maryland on their long-distance network, then handed off to local carrier Verizon for termination at Coloco's Laurel facility.

And Back to Dial Tone
At our Laurel facility, our island customer's long-haul international circuit is plugged into another Cisco Series 3660 Multiservice Platform router, which they colocate here. It is connected through a T1 card with an integrated CSU/DSU. The integrated T1 card with CSU/DSU offers two advantages. First, it has enough "intelligence" to understand and work with the complexities of fractional T1 circuits. Secondly, the card can be remotely monitored and diagnosed over the Internet, a capability not easily integrated into stand-alone CSU/DSU hardware.

Inside the router, the data is passed along to the appropriate ISDN T1 PRI cards, which convert the VOIP packets into voice-quality telephone calls. The Cisco Series 3660 supports multiple ISDN PRI cards; the client current has two PRI cards installed with two more on order. Each U.S. standard PRI can support up to 23 voice calls or "channels"

A simple piece of Category 5 cable connects each ISDN PRI card over to Coloco's Summa Four telephone switch. The telephone switch is connected to the rest of the public switching telephone network (PSTN) through multiple telephone carriers, thus allowing the customer to have wholesale U.S. phone service.

The SS7 compatible switch assigns DID numbers to the ISDN PRI service to keep track of inbound and outbound telephone calls. It also handles 800 number routing. The island nation has a total of three different inbound 800 numbers and calls from each of the numbers are mapped to three different unique telephone extensions B.B" three different call centers B.B" in the country.

Right Next Door
By using a unique combination of colocation and telephony services, the island nation can provide 800 number service within the United States for their three natively-located call centers while at the same time getting nearly four times more calling capacity out of their bandwidth than they would with traditional telephone circuits.

Advantages of Voice over IP (VOIP)
Using voice over IP technology provides a number of advantages over so-called "traditional" telephone technology. Such advantages include:

Internet Bandwidth exists as a backup path for phone calls
If the dedicated connection of several thousand miles across the ocean should happen to be disrupted somewhere, IP telephone calls can automatically fall back to the Internet "cloud."

Best way to "compress voice" for more capacity over existing lines
By using 1 Megabit of bandwidth and VOIP technology, approximately two-thirds or sixteen (16) unique channels on a US-standard T1, the island nation can effectively put sixty (60) phone calls onto the same bandwidth, resulting in a ratio of nearly 4:1. According to users on in the United States and on the island nation, there is no audible difference between "normal" calls and voice over IP calls.

With limited resources, voice calls could be compressed further - with some loss of audio quality - to fit anywhere from eight to ten simultaneous phone calls onto a single 56/65Kbps leased line, affording even a very resource-constrained venture some options.

Implementation is simpler and faster than traditional technology
For testing and implementation purposes, it is much easier to set up a single data leased line rather than having to setup voice circuits, switch between European and U.S. voice standards, and then route the resulting calls in and out of a U.S. based PBX.

Other Applications
This particular application of colocation services, VOIP technology, and SS7 telephony is perfect for overseas call centers with the appropriate PBX capabilities.

Other businesses that could take advantage of these services include:

  • Domestic Call Centers
  • Long-Distance Carriers
  • Large businesses wanting redundant diversely-routed phone services
  • Companies that do extensive business with Washington-Baltimore entities (government contractors, importers, etc.)