I see a lot of companies buying softswitches and it makes me wonder if it might not be a better economic idea to share a switch with somebody else. There is so much potential for savings that anybody thinking of installing one should consider it. In the following I will discuss what it means to share a softswitch and look at the pros and cons.

The Basic Requirements. Sharing requires that somebody already owns a softswitch that can control geographically separated gateways. Such a switch must be able to share both the inter-machine trunking gateways, which facilitate PSTN interconnection and the media gateways which facilitate interconnection to customers. Sharing is also going to require interconnection between the two sharing parties. This means there must be some sort of trunking established between the two parties that can be either traditional TDM trunks or IP trunks.

What Would be Shared. The following elements are the components of a softswitch that can be shared, meaning that only one of each of these needs to be purchased:

• Core softswitch – the device that contains subscriber and routing information;
• Feature Server – the device that facilitates phone features;
• Session Border Controller – the device that provides security between the softswitch and the gateways, some CPE and other networks;
• Signaling Gateway – the device that interface with the SS7 network;
• Unified Messaging or Unified Communications server – the device that stores, controls and converts data used in unified communications services like voice mail, email notifications, voice to text and text to voice, etc.

What the Second Company Needs to Buy. If you are going to share somebody another softswitch you only need to buy a few components. These are referred to as the distributed elements in a softswitch network. The two elements that you must buy are:

• Inter-machine Trunking Gateway – for local interconnection to the PSTN. This lets the lessee still connect to the world using the same connections in place your legacy switch;
• Media Gateway – for local connection to local distribution network and/or CPE.

Data connections required. As mentioned, there must be a data connection established between the softswitch and the new location that allows communications between the shared elements housed at the core softswitch and the distributed elements found at the new location. The size of the data pipe/connection required depends on the amount of data required between the shared and distributed elements. It only requires a few megabits per second to transmit voice traffic. You’ll need a connection in the tens of megabits per second if you are using a lot of features like voice mail & unified communications or a lot security invocation.

Partitioning. The owner of the shared elements will have to ‘partition’ the shared elements in order to ensure that subscribers of the sharing company can’t be seen or manipulated by other sharing companies; Partitioning will also hide the call detail records, routing control and will make sure that the shared elements can communicate through to the multiple networks operated by the sharing companies.

How to Determine if Sharing is the Right Idea. The big benefit is the savings, but there are other considerations:

• It is inexpensive to buy only the distributed elements. Depending on how large you are, the distributed elements could cost anywhere between $25k and $200k which is far less than buying a new softswitch.
• What is the cost of the data connection needed to connect the two locations? Generally companies make these connections using establish Internet backbone and this typically adds nothing to that cost.
• How much does the switch owner want to charge for using the softswitch core? There are many ways to charge for this service. It could be done on a flat rate monthly lease, a connection fee per telephone number.
• Reliability. How good is the Internet connection between the two companies? If that connection is lost then voice processes will stop. Ideally the connection ought to be on a ring or have redundant routing.
• Control. I often hear a company thinking of leasing say that they feel like they don’t have enough control in a shared switch. But you can get access to all important switch functions remotely.

When I look at the numbers I find that it is almost always better to share a switch rather than to buy a whole new switch. However, the one factor that still often drives the decision to buy a new switch rather than share is the reliability of the data connection between the two parties. But this is generally about the same reliability as connecting remote switches in your own network to a host switch.

If you want to consider sharing a softswitch call CCG and we can help you work though this decision.