In classical DID, a company receives an area code, a prefix, and a block of the four-digit numbers which come after the prefix from the phone company. They then assign either the last four or the last five digits that terminate each of their assigned numbers to each employee as their internal extension. After this is done, their PBX is programmed to transfer a call to an employees extension if only the four or five digits of the extension are dialed from inside of the company or to ring the extension if the full 11- or 7-digit number is dialed from outside of the company.

For example, suppose a company has the area code 650 and receives the prefix 221. An employee who was at his desk and whose extension was 4175 could be reached when anyone inside of the company dialed 4175; and if anyone outside of the company dialed 1-650-221-4175, the employee's desk phone would ring directly without passing through either an operator or Auto-Attendant.

This is called Direct Inward Dial since anyone, anywhere in the world, can reach an extension in the company by dialing the complete phone number of that extension, but anyone inside or the company only needs to dial the last four digits.

When a company subscribes to the Virtual PBX® service, they receive an 800/888/877 number which is connected to a group of virtual extensions. Each extension can store up to four contact phone numbers which the Virtual PBX® tries in turn until the person is reached. When a customer dials the Virtual PBX® number he normally reaches the company's Auto-Attendant and has the choice of dialing an extension directly, using the company directory to spell the name of the desired employee, pressing a menu item for Sales, Customer or Tech Support, etc., or 0 for the operator. When this is done he is connected to the appropriate contact phone number of the employee selected by the above choices.

VirtualDID bypasses the Auto-Attendant and rings the extension directly provided that the calling number has been pre-assigned to the extension.

Using the VirtualDID feature of the Virtual PBX®, it is possible to set up a system such that a customer can dial the existing or old company DID number and reach the desired employee no matter where he is in the world.

To set up a system so that anyone who calls, for example 1-650-221-4175, can always reach the given employee:

• Set up the virtual extensions. The most convenient way to do this is to make the virtual extensions the same as the original company extensions, in the case of the example, 4175, etc.
• Enable the VirtualDID function so that it automatically routes anyone calling 1-650-221-4175 to the Virtual PBX® extension, 4175.
• Forward 1-650-221-4175 to the Virtual PBX® 800/888/877 number. The way that forwarding works is that 1-650-221-4175 is sent down the line as the calling number and not the original number of the caller. Thus the system knows which number was dialed whether Caller ID is blocked or not.
• There are two ways to forward a DID number: 1) Forwarding by the local phone company and 2) Forwarding by the company PBX. Many local phone companies cannot forward individual DID numbers. When this is the case, the extension owner must forward calls to the company's Virtual PBX® number using the forwarding feature of the company's PBX equipment. The advantage of this second method is that either a DID call from the outside to the extension or a call from inside of the company using, for example, just the last four digits of the DID number will both ring the Virtual PBX® and thus be forwarded to all contact phone numbers stored with the extension.
• There is one problem with the second method of forwarding: some hardware PBX manufacturers always send the same calling number down the line instead of the calling number of the extension owner. In this case, the Virtual PBX® does not know to whom to route the call. When the hardware PBX functions in this manner, please contact VirtualPBX.com's Tech Support staff as we have a solution for this case.
• Store contact phone numbers in the Virtual PBX® extension as required. For example:
  1. If the employee is working at his office, he would store his office number in Contact Phone No. 1 (caution, see below), his cell phone number in Contact Phone No. 2, and his home phone (if desired) in Contact Phone No. 3.
  2. If the employee is temporarily working in a foreign country, he would store his international work number in Contact Phone No. 1, his rented cell-phone number in Contact Phone No. 2, and his temporary home phone number (if desired) in Contact Phone No. 3.
  3. If the employee is traveling on business he would store his rented cell-phone number in Contact Phone No. 1, his international hotel and room number in Contact Phone No. 2, and the phone number of the person that he is visiting in Contact Phone No. 3. The hotel number will ring him directly in his room if the hotel has either Direct Inward Dial to his room or Dial Through an Auto-Attendant with the room number as an extension.

When the above steps are taken, anyone dialing 1-650-221-4175 will reach the employee no matter where he is. Imagine having someone dial an employee's home-office number in the U.S. and the rented cell phone in his pocket in Hong Kong rings.

There is one danger in this system: if the employee is working at his company home office and wishes calls to reach him there, he cannot store 1-650-221-4175 in his contact phone numbers. Should this be done, the system would then be circular; and calls to 1-650-221-4175 would be continually forwarded to the Virtual PBX® and never reach the extension on the desk. This can be avoided by special features of the Virtual PBX®. The extension owner can:

• Use the company's main number plus his extension provided the main number is answered by an Auto-Attendant and not by a live operator. The Virtual PBX® has a "Wait-for-Answer" character and a "One-Second-Pause" character. In this case, the correct number to store in the contact phone number is [Company Main Number] [Wait for Answer] [Pause as needed] [Extension Number]. For example in the above case, assume that the main company number is 1-650-221-3000. The number stored in the contact phone number would be 16502213000#2*2*24175. #2 is the "Wait-for-Answer" character, and *2 is the "One-Second-Pause" character. In this example a two-second pause was inserted to give the Auto-Attendant a chance to begin speaking before dialing the extension. Whether a pause is needed at all and how long will vary from system to system and must be determined by trial and error. Caution: this method will not work if the forwarding has been done inside of the company's PBX and not by the local phone company.

If the forwarding can be done outside of the company by the local phone company, this first method is by far the best way to avoid a circular loop, but this many not be possible and many companies still use a live operator to answer the main number. The balance of the methods described below would be used if either of the above situations happens to be the case.

• If the company has a second main number which does use an Auto-Attendant, store that number with the "Wait-for-Answer" and the extension instead of the published number.
• If there is a second phone in the office, store that number for the contact phone number.
• If two different numbers in the PBX ring the same office phone, use the second number. Some commercial PBXs used two numbers for the same extension phone to mechanize Call Waiting.
• Store the employee's cell phone number for the contact phone number instead of the office extension.
• Turn off the forwarding when in the home office. This is the most inconvenient way around this problem and should only be used as a last resort.

If the forwarding has been done by the local phone company outside of the company, then any person inside of the company who wishes to reach an employee who is not at his desk or is away on travel or on temporary assignment must either dial the full 1-650-221-4175 number or the Virtual PBX® 800/888/877 number followed by the virtual extension, in this case 4175. Anyone in the company can still dial 4175 directly and have the phone in the office ring, but doing this will not search the contact phone numbers. One of the two numbers above must be dialed to enter the Virtual PBX®.

If the forwarding has been done inside of the company by the company extension owner, then an employee inside of the company dialing either 1-650-221-4175 or just 4175 would reach the Virtual PBX® and find the desired person no matter where he was in the world.

Also see the tutorial Traveling Internationally and Receiving Calls and the usage scenario International Offices World Wide Connected by a Single Business Telephone Number.

When a new Virtual PBX® system is set up, our technical support personnel do the initial setup and can help with the details of managing the system or an extension.