It sounds like you're looking to integrate your database application with Teams Telephony in a similar way to how it currently works with your old telephone system via a TAPI driver. Unfortunately, Teams does not support TAPI .
However, there are other interfaces and APIs available that can help you achieve similar functionality:
Microsoft Graph API: This API allows you to manage Teams calls and meetings programmatically. You can use it to initiate calls, get notifications of incoming calls, and more. For example, you can set Teams to respond to tel: URIs, which allows desktop applications to dial out.
Azure Communication Services (ACS): ACS provides APIs to manage Teams Voice over IP calls, Teams phone calls, and Teams meetings. This can be integrated into your applications to provide telephony capabilities.
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