Azure Communication Services Call Latency

Hello Bhargavi Naragani,

Thank you so much for your response. I appreciate your feedback and will attempt to answer your questions.

My call setup process is as follows. Please let me know if my setup can be improved.

private void StartCall(string targetPhoneNumber, string acsPhoneNumber) 
{
    var target = new PhoneNumberIdentifier(targetPhoneNumber); // PTSN phone number
	var caller = new PhoneNumberIdentifier(acsPhoneNumber);  // Azure Communication Service Phone Number
    var callInvite = new CallInvite(target, caller);

    CreateCallOptions options = new CreateCallOptions(callInvite, new Uri(callback));
    CreateCallResult createCallResult = await client.CreateCallAsync(options);
    
    _CallId = createCallResult.CallConnectionProperties.CallConnectionId;
}
 
private void AddCaller(string targetPhoneNumber, string acsPhoneNumber) 
(
    var existingConnection = client.GetCallConnection(_CallId);
    var target = new PhoneNumberIdentifier(targetPhoneNumber); // PTSN phone number
	var caller = new PhoneNumberIdentifier(acsPhoneNumber);  // Azure Communication Service Phone Number
    var callInvite = new CallInvite(target, caller);
    AddParticipantOptions participantOptions = new AddParticipantOptions(callInvite);
    AddParticipantResult result = await existingConnection.AddParticipantAsync(participantOptions);
}
   

I'm unaware of the interactions between the signaling layer and media transport. Do you know of any documentation that can help point me in the right direction to optimize this?

If you have any docs on how to configure proper QoS for my Azure setup to prioritize voice traffic, that would be great. I assumed that Azure Communication Services would handle network operations, so I haven't looked into this.

Both calls are established from Azure Communication Services to PTSN telephones. I'm not sure how I would go about checking the network latency at both ends? A telephone cannot provide network statistics and neither participant even requires a network connection.

The geographic locations of the participants are somewhere in the United States, so there could be as much as 3500 miles between participants. Is there anything I can do to reduce latency due to distance? Maybe there is a relationship between the Azure Communication Services configuration and the location of the participants? Can you provide any insight?

I don't know of any network appliances between the participant's PTSN telephone and Azure Communication Services. Participants are using telephones connected to public telephone services.

Neither participant has a broadband connection. The calls are being received on their PTSN telephones, so I'm assuming the quality of their broadband connection (if they had a broadband connection) doesn't apply.

I have noticed no change in latency during different times of the day.

Look forward to your reply!

Thank you!

-Dave