1. User guide
   1. 1 Overview
   2. 2 Getting started
      1. 2.1 Connecting
      2. 2.2 A simple overlay
      3. 2.3 Moving an overlay
      4. 2.4 Canceling an overlay
      5. 2.5 Overlaying multiple numbers
      6. 2.6 What next
   3. 3 A more advanced overlay
      1. 3.1 Call announcements
      2. 3.2 Call recordings
      3. 3.3 Advertisers
      4. 3.4 Expiry options
         1. 3.4.1 Setting an expiry
         2. 3.4.2 Enforcing the expiry
         3. 3.4.3 The called extension
      5. 3.5 Restricting calls
         1. 3.5.1 Who can call
         2. 3.5.2 The length of calls
         3. 3.5.3 The number of calls
   4. 4 Advertisers functions
      1. 4.1 Create an advertiser
      2. 4.2 List advertisers
      3. 4.3 Edit an advertiser
   5. 5 Sound file functions
      1. 5.1 Pre-call anouncements
         1. 5.1.1 Create an announcement
         2. 5.1.2 List announcements
         3. 5.1.3 Edit an announcement
         4. 5.1.4 Delete an announcement
      2. 5.2 Call recordings
         1. 5.2.1 Get recordings
   6. 6 Statistical functions
      1. 6.1 Call statistics
         1. 6.1.1 Raw statistics
         2. 6.1.2 Grouped statistics
      2. 6.2 Overlay statistics
         1. 6.2.1 Count your overlays
         2. 6.2.2 List your overlays
      3. 6.3 Real time reporting
   7. 7 Miscellaneous functions
      1. 7.1 Check values
         1. 7.1.1 List number types
         2. 7.1.2 List number classes
         3. 7.1.3 Check a parameter
      2. 7.2 Check settings
         1. 7.2.1 Check your permissions
         2. 7.2.2 Check your settings
         3. 7.2.3 Check call costs
         4. 7.2.4 Check costs for a call
      3. 7.3 Check previous requests
         1. 7.3.1 Count previous requests
         2. 7.3.2 List previous requests
         3. 7.3.3 View request details
   8. 8 Glossary

3.4.2 Enforcing the expiry

When an overlay expires it is not deallocated from the destination. It is simply marked as available, so future overlay requests can use the number. If a call, or an overlay request with the same reference string, is made before the number is reassigned then the original overlay will be honoured. Usually this is useful as it reduces the chance of a user getting a wrong number, however you may wish to insist that an overlay can only be called within a certain timeframe.

Example

Restrictions of an external system mean that we only want to allow users to call a certain destination for the next hour. We can provide the 'expires' parameter to allow the overlay to expire after this time, but later calls could still be put through. As we don't want that to happen, we will also provide the enforceExpiry flag so that later calls are rejected.

• The unix timestamp that the overlay should expire: expiry=1714095439
• The enforceExpiry flag: enforceExpiry=1

Note, by default the life of an overlay is automatically extended when it is called. If you are setting this flag, you will probably be interested in the calledExtension parameter.