ACS Automation slow to respond

Hi There,

My team is looking to use the ACS for some calling scenarios to the PSTN using the Automation API with webhooks for events. We have noticed that there are some (2-3 second) delays between requests from the automation API and their corresponding events coming back over the webhook.

For example when the call is offered from the SBC to the MS SIP Proxy the incomming-call notification takes 2 seconds to arrive back at our application; we send an AnswerCall request to the ACS it takes a further 2 seconds for the SBC to receive the 200 OK MS SIP Proxy and a further 2 seconds for the Answed event to come through in a webhook. Then play a message to the caller which takes another 2 seconds to start coming through.

It all adds up; and it takes ~8 seconds between receiving a call and playing the first message which is a pretty long time in the world of voice.

I'm certain this is not an issue with the SBC as we tried a MS provisioned local phone number with similar results (bypassing direct routing entirely). I've checked the eventgrid and ensured that there is no batching enabled and all the latency metrics are coming back with no latency and no failed deliveries.

Does anyone have experience with this?