Simton IPX can inter-work with a local PSTN network. It can be assigned with local phone numbers and communicate with any wire-line phone or wireless phone. When an external call comes in, the caller can dial a local or remote extension as if they were the same. The caller can hear a customized greeting or be directly connected to the operator. The Simton IPX system can also be configured to automatically direct calls to a virtual attendant or a voicemail system.
A Simton IPX based voice intranet can be composed of many IPX’s deployed in different geographic locations or countries. They serve as a virtual wide-area PBX. The virtual wide-area PBX has phone numbers and connections to the PSTN network of different countries, which become common resources for every extension on the entire network. From any extension, calling external phones of another country is convenient and free of charge.

Figure 6 Voice Intranet inter-work with PSTN

In Figure 6, extension 101 in city A can call an external number in city B through the IPX in city B. Communication between city A and B is free of charge. All extensions 101, 102, 201, 202, 301, and 302 share the same external numbers 8651085219582, 862152657775 and 17817521110. For example, in city C, a company’s customer can call a local phone number to reach the company, but the customer service team could be at another branch or anywhere in the world. 
If a salesperson has a small IPX, he could go anywhere as long as he had an internet connection. He could make calls back to his home city free of charge. The people at his home city could still call his local phone number to easily reach him.

In many countries, new emerging Internet telephony service providers offer normal phone numbers and phone services the same way as traditional telephone services do, but over the Internet. The advantages of subscribing to Internet phone services include cheap communication costs, the ability to have simultaneous calls, the ability to have multiple phone numbers, and a wide variety of services.
Simton IPX can work with any internet phone service provider. Multiple IP phone service accounts can be configured on the Simon IPX. Some accounts may have very good rates to certain countries, while others have better rates or quality for local calls. The user can set up dialing policies to ensure that calls to different destinations can automatically go through the most efficient IP phone service account.

Figure 7 VoIP Service Accounts

In Figure 7, the IPX has both Chinese and American VoIP accounts. The extensions exist as if they were in the respective countries the accounts are held in. Thus, an external caller can call into any extension via the VoIP account that is in the same country as the caller. Likewise, an extension can call out using either VoIP account, and thus the call will not be charged for long distance.

Communication between IPX’s is free, but call-in/out of an IPX network may or may not be free, depending on the cost of the service needed to reach such an outside area. In other words, the use of external resources may involve some costs. Simton IPX has a mechanism that administrates the usage of external resources that prevents the unauthorized use of external resources.

Figure 8 External Calls Authentication

There are many ways an extension can use the resources of the voice intranet. A local extension can call both local and remote external numbers. In the latter case, long distance calls are charged as if they were local calls. An external caller from one IPX can call an external location at the other IPX by going through the IPX’s. In this way, any two callers with access to connected IPX’s can make long distance calls as if they were local.
Simton IPX has the ability to authorize the usage of voice intranet resources and to generate the accounting records of the usage of such resources. The employees of a company, the employee family members, the partners of the companies, and people on business trips can be assigned a username and password individually, so that they can take advantage of the IPX intranet’s resources. Meanwhile, the cost of long distance calls can be avoided.

When all the features and capabilities of the voice intranet are put together, the IPX systems in different locations form a wide area IP PBX as the following figure.

Figure 9 Wide Area IPX

All extensions within the voice intranet work together as they would in the same building. One operator or reception serves the for entire organization including remote offices. All PSTN lines in different countries are the local lines to everyone in the organization. External calls from any of those countries can reach anyone in the organization. External calls can be rerouted out through another interface in another country.