---
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title: Optional Call Center Elements and Attributes
collection: developer
version: current
locale: en-us
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canonical_url: https://developer.salesforce.com/docs/service/api-cti/guide/sforce-api-cti-call-def-file-optional.html
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content_type: documentation
content_hash: cbd7ea2999faf84c56015aff73eb400a26614b20e3f2f8d34fbb2ad31a0f545a
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  - Open CTI Developer Guide
  - Service Cloud Developer Content
---

# Optional Call Center Elements and Attributes

The call center definition file can include optional `<item>` elements in the `<section>` element.

In addition to the required elements, you can add optional elements to configure a softphone.

**important:** The way you implement Open CTI depends on your org’s user interface. There are separate Open CTI APIs for Salesforce Classic and Lightning Experience. The `reqSalesforceCompatibilityMode` item in your call center definition file identifies the user interface you plan to use—Salesforce Classic, Lightning Experience, or both. If no value is specified, the default is `Classic`. This item is optional, but to make calls in Lightning Experience you must specify `Lightning` or `Classic_and_Lightning`.

|\<item> Name|Description|Supported in Salesforce Classic|Supported in Lightning Experience|
|--------------|-------------|---------------------------------|-----------------------------------|
|`reqSalesforceCompatibilityMode`|Determines where the softphone is visible. If no value is specified, the default is `Classic`.<ul><li>To display the softphone in Lightning Experience, specify `Lightning`.</li><li>To display the softphone in Salesforce Classic, specify `Classic`.</li><li>To display the softphone in both user interfaces, specify `Classic_and_Lightning`.</li></ul>|![Checkmark icon](https://developer.salesforce.com/docs/media/checkmark_16x16.png)|![Checkmark icon](https://developer.salesforce.com/docs/media/checkmark_16x16.png)|
|`reqStandbyUrl`|Represents the location that hosts the secondary softphone. The standby softphone is used after the timeout period for the primary softphone has elapsed and the [notifyInitializationComplete() for Salesforce Classic](https://developer.salesforce.com/docs/service/api-cti/guide/sforce-api-cti-notifyinitializationcomplete.md) method hasn’t been called within the required timeout period. When you specify a standby URL, you must also specify the `reqTimeout` field.|![Checkmark icon](https://developer.salesforce.com/docs/media/checkmark_16x16.png)|![Checkmark icon](https://developer.salesforce.com/docs/media/checkmark_16x16.png)|
|`reqTimeout`|Represents the time in milliseconds after which the standby URL is used to host the softphone. Before the timeout period has elapsed, the softphone displays a loading icon indicating that the softphone is initializing. When you specify a required timeout, you must also specify the `reqStandbyUrl` field.|![Checkmark icon](https://developer.salesforce.com/docs/media/checkmark_16x16.png)|![Checkmark icon](https://developer.salesforce.com/docs/media/checkmark_16x16.png)|