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Switchvox® Appliance Sizing Guide

Switchvox® Appliance Sizing Guide

Digital Techniques and Digium provides maximum-use specifications, such as number of extensions, concurrent calls, recordings, and conference participants, about each of our Switchvox appliances. These specifications are useful to get a big picture view of what the appliances can do. In this guide, we provide additional considerations that can help you decide which Switchvox appliance is the right size for your company.

The Basics

Published Activities

  • “Concurrent calls” refers to the number of calls that are active at the same time. This does not mean that these calls started all at the same time.
  • Any time a phone rings, that is considered a call. For Ring All activities or Intercom/Paging extensions, each ringing extension is also considered a call. (Also, see the Ring All, Paging, and Intercom section to the right.)
  • “Recorded Calls” refers to the number of the concurrent calls that are being recorded.
  • “Conference Participants” refers to the number of the concurrent calls that are part of a conference call.

Our assumptions

Our appliances can support the usage specifications we publish, assuming that the following is true:

  1.  They are the only activities taking place on the system. However, this may be a rare occurrence, so an appliance should always have room for additional activity.
  2.  A Digium phone is registered to every phone extension.
  3.  Calls are created approximately every 5-10 seconds, but not all at the same time.
  4.  Many of the Digium phones have up to 15 subscribed contacts that are making the concurrent calls (so they are actively changing Status).
  5.  Many Switchboards are open and using the same Phonebook used by the Digium phones, and are actively changing Status.

Additional considerations when sizing Switchvox appliances

Ring All, Paging, and Intercom

Actions that ring or call multiple extensions at once are more resource-intensive because multiple calls begin at once. If the extensions involved are also subscribed on Digium phones and/or on Switchboards, then a number of events are using system resources all at the same time. In these situations, it is best to purchase a larger appliance to accommodate this activity. Ensure that the maximum number of extensions in a “ring all” queue does not exceed the maximum number of concurrent calls recommended for the appliance.

If this is not possible, choose a ring strategy that will bring the maximum number of concurrent calls within the recommended specification.

Contacts and Phonebooks

When users set up a Phonebook and use it on their Switchboard or Digium phone, the Phonebook’s contacts (entries) are often subscribed—meaning, the contact’s Status is shown in real-time. Sending that Status information to every Digium phone and/or Switchboard Phonebook panel in real-time is resource-intensive. Consequently:

  • If one user is reasonably active, and is a subscribed contact on one Digium phone and one Switchboard panel, this consumes limited resources.
  • If a user is very active and is a subscribed contact on multiple Digium phones and Switchboard panels, that one person’s activity consumes a much larger quantity of resources.

For example, the person is on and off the phone, changing to Available, Do Not Disturb (DND), Away, etc. The more activity a person has, the more information the server must handle.

“Subscribed” means that the contact’s Busy Line Field (BLF) indicates phone-status, and the contact’s icon indicates Jabber status.

  • Digium phone. The contact on a Digium phone is subscribed for real-time Status changes.
  • The number of subscribed contacts is controlled by the extension’s Phonebook Option Number of Rapid Dial Subscriptions, and by the contact’s position in the Phonebook. While the D50 and D70 phones clearly show access to subscribed contacts on the BLF keys, D40/D45 phones do not. However, it’s possible for a D40/D45 to have many subscribed contacts, even though Status isn’t visible at a glance.
  • Switchboard. Contacts exist in the Phonebook panel of the Switchboard. Every Phonebook entry in a Phonebook panel is subscribed, so any Status change for the entry requires hardware resources.

For systems with very active users and/or a large number of Switchboard users, consider proposing a larger appliance. An appliance sized to meet only the number of concurrent calls may not be large enough to meet the needs of organizations with many active users and Switchboard users.

Also, care should be taken when creating Phonebooks that will be utilized by a Digium phone. Ensure that only the minimum number of contacts that will be used by the Digium phone are included in the Phonebook.

Queues and Queue Displays

A customer requiring a large number of queues is an indicator of a resource-intensive scenario. The requirement for more than 10 queues should raise consideration for the number of hardware resources required in the Switchvox appliance.

Using the Switchboard queue panel and/or the Digium phone’s queue application is also resource-intensive. Queue statistics generate real-time information that is shared with all users accessing queue panel and queue phone applications.

For systems with more than 10 queues, or systems with many users accessing the queue panels and/or queue applications on the Digium phone, special consideration should be given. Consider a method to reduce the number of queues, and/or propose a larger appliance. An appliance sized to meet only the number of concurrent calls may not be large enough to meet the needs of organizations with many queues that are monitored by many people.