Graph API: create a PSTN call and invite a PSTN participant

Any update?

A peer-to-peer bot to PSTN call, works as expected, but we receive the following exception when adding a PSTN participant into a group call:

Code: 403
Message: Unexpected 'Failed' status for operation eb8990a2-4dd0-48f8-b171-01ae9092696b:
addParticipants failed for participant 4:+4xxxxxxxxxx. Underlying reason: Forbidden. DiagCode: 403#10151.@
AdditionalData:
subcode: 10151

"@odata.type": "#microsoft.graph.commsNotifications",
"value": [
{
"@odata.type": "#microsoft.graph.commsNotification",
"changeType": "Deleted",
"resourceUrl": "/communications/calls/06206100-0f1d-44dd-88ff-80a5610d7637/operations/9ace7412-7553-4246-b232-80ed4a0f5a35",
"resource": "/app/calls/06206100-0f1d-44dd-88ff-80a5610d7637/operations/9ace7412-7553-4246-b232-80ed4a0f5a35",
"resourceData": {
"@odata.type": "#microsoft.graph.inviteParticipantsOperation",
"participants": [
{
"@odata.type": "#microsoft.graph.invitationParticipantInfo",
"identity": {
"@odata.type": "#microsoft.graph.identitySet",
"phone": {
"@odata.type": "#microsoft.graph.identity",
"id": "+4xxxxxxxxxx"
}
},
"participantId": "f6d17697-0b8c-4f89-946b-b04d43a5d658"
}
],
"clientContext": "f3d0bc58-09c9-4887-8244-c4aaf6fb02b8",
"resultInfo": {
"@odata.type": "#microsoft.graph.resultInfo",
"code": 403,
"message": "addParticipants failed for participant 4:+4xxxxxxxxxx. Underlying reason: Forbidden. DiagCode: 403#10151.@",
"subcode": 10151
},
"status": "Failed",
"id": "9ace7412-7553-4246-b232-80ed4a0f5a35"
}
}
]

Thank you!