Create call to PSTN number fails with CreateUsageRequest: Balance not found error

Describe the issue
I'm trying to make my bot ApplicationInstance call a PSTN number. Some days ago it worked successfully, now it doesn't work anymore.

Code Snippet
Invoking POST on https://graph.microsoft.com/v1.0/communications/calls endpoint using Postman with the following body

{ "@odata.type": "#microsoft.graph.call", "callbackUri": "<CALLBACK_URI>", "source": { "@odata.type": "#microsoft.graph.participantInfo", "identity": { "@odata.type": "#microsoft.graph.identitySet", "applicationInstance": { "@odata.type": "#microsoft.graph.identity", "displayName": "Calling Bot", "id": "<APPLICATION_INSTANCE_ID>" } }, "countryCode": null, "endpointType": null, "region": null, "languageId": null }, "targets": [ { "@odata.type": "#microsoft.graph.invitationParticipantInfo", "identity": { "@odata.type": "#microsoft.graph.identitySet", "phone": { "@odata.type": "#microsoft.graph.identity", "id": "PSTN_NUMBER" } } } ], "requestedModalities": [ "audio" ], "mediaConfig": { "@odata.type": "#microsoft.graph.serviceHostedMediaConfig" }, "tenantId": "<TENANT_ID>" }

Expected behavior
A call to the specified PSTN number should be made

Graph SDK (please complete the following information):
Microsoft Graph 3.18.0

Call ID
Call ID ba1f5d00-d6f8-4cda-98e0-de72e1850587 @ 07:26:20 UTC, 18 October 2021

Logs
The BOT notification endpoint receives the following error
{ "@odata.type": "#microsoft.graph.commsNotifications", "value": [ { "@odata.type": "#microsoft.graph.commsNotification", "changeType": "deleted", "resource": "/app/calls/ba1f5d00-d6f8-4cda-98e0-de72e1850587", "resourceUrl": "/communications/calls/ba1f5d00-d6f8-4cda-98e0-de72e1850587", "resourceData": { "@odata.type": "#microsoft.graph.call", "state": "terminated", "resultInfo": { "@odata.type": "#microsoft.graph.resultInfo", "code": 404, "subcode": 9999, "message": "Error from CreateUsageRequest:\r\nBalance not found. DiagCode: 404#580406" }, "callChainId": "30a35c10-44b2-4026-a9f5-cc8986f881c0", "terminationSender": { "@odata.type": "#microsoft.graph.identitySet", "phone": { "@odata.type": "#microsoft.graph.identity", "id": "<PSTN_NUMBER>", "displayName": "PSTN_NUMBER", "identityProvider": "None" } } } } ] }

Additional context

The ApplicationInstance used in the request has the following licenses assigned to it via the Office 365 admin portal:

ApplicationInstance has a phone number assigned to it (sensitive data blurred for privacy)

Start by reproducing the POST request to /v1.0/communications/calls in Postman and compare the terminated call notification with the reported CreateUsageRequest and Balance not found message. Review the ApplicationInstance licensing and phone-number assignment details shown in the issue. Done means identifying a documented configuration or service cause; the payload does not name a repository file or test.