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Gasmanz
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Joined 7 years ago
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No MoH from SBC when transferring
Found an interesting scenario that breaks your SBC MoH for call transfers. If you are using the Teams desktop client to answer calls, and you happen to put a call on hold and then resume it, you will then no longer receive re-invites from Teams when you press the Transfer or Consult then Transfer buttons for the rest of the call. This means your SBC has no idea that it is meant to start the local playback of its local MoH file for transfers. This will only happen if you put a call on hold and resume it before attempting transfers. If you attempt a transfer without using hold beforehand then there is no issue. It seems that Teams no longer sends re-invites for calls that are placed on hold and resumed in the desktop client, but then it forgets that it's meant to do it if you want to transfer the calls afterwards. Not and issue on the Poly CCX 400 desk phones that I tested with as they still send re-invites for call hold and resume. Has anyone else come across this and is there anyway to change the Teams behavior of no re-invites for Hold and Resume with the desktop clients? I have tested this on 2 separate Teams tenants with SBCs from different vendors for validation.Re: Music on hold for regular Teams calls
Your SBCs should be able to fill the gap for MoH on Transfers for the time being. They should have the ability to look in the SDP coming from Teams for a=inactive and then play an MoH audio file to the external party while they wait for the transfer to complete. If you have a 3rd party looking after your SBCs you should be talking to them about this function.29KViews0likes5CommentsRe: PSTN Call Drops if you do consult transfer - Direct Routing
Andrew_Naydonov Thanks for the reply. Seems like I'll have to do some deeper diving now that we have also reverted our trunks to auto but no change in behavior. We'll be reviewing our Oracle SBCs config with the vendor to see if something has changed or if any config elements are causing this.4.3KViews0likes0CommentsRe: PSTN Call Drops if you do consult transfer - Direct Routing
Hi Andrew, We have had the same issue reported to us by one of our Australian customers on Teams. The test calls that we did seem to point at an issue in Teams connecting the calls, as the SIP legs on the SBCs look completely normal. Do you have the Direct Routing trunks manually set to use the AU media servers or are they on auto? We have ours set manually to AU and are wondering if this may be the cause. Did you resolve the issue or is it still existing for you?4.3KViews0likes2CommentsRe: Music on Hold in Teams & 4 seconds until Hold is in place for caller
VickiFHL We are still seeing on hold delays of 3-10 seconds for Teams Direct Routing calls to individual users. I have also been talking to our SBC support about the transfer silence issue. They have advised that some Telcos actually inject their own MoH when Teams sends a re-invite after the user presses "Transfer" in the Teams client. The 2 largest Telcos in Australia (Telstra and Optus) do not inject their own MoH for re-invites they receive that have a=inactive or a=sendonly in the SDP. For these carriers and many others, you need the SBC to intercept these re-invites and inject a MoH audio stream on behalf of the Teams user. If injecting your own MoH at the SBC you may have an issue for blind transfers. Blind transfers start with a re-invite from Teams on first "transfer" button press, but then after you enter the phone number and press "transfer" a second time to complete the transfer, Teams sends a refer with no SDP to notify the SBC that a=sendrecv now. Could be that some SBCs are able to deal with this however. It would be good if Teams actually acted more like a PBX and did this stuff on its own.19KViews0likes1Comment
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