Draytek VirgorPhone 350 Attended Call Transfer

[daniel.hayman]

Hello,

I am setting up my office phone system on 3cx. I have a mixture of draytek vigorphone 350, yealink t21 and yealink t22 phones.

In my testing I have found that when making an attended call transfer from a draytek phone to draytek phone the call gets lost and remains on hold until the caller hangs up. If I do an unattended transfer everything works ok.

I have tested both attended transfer and unattended transfer between yealinks and yealinks to drayteks and everything works OK.

Within the extension module I have checked the box next to 'Supports Re-Invite' which has made no difference.

I have 3CX hosted on AWS, and the firewall checker runs OK on the 3CX webpage.

Thanks
Dan

 

[NickD_3CX]

Hi Dan,

When performing the Attended Transfer, does the number you are transferring to answer the call before completing the transfer from the extension doing the transfer?

I have no experience with this phones at all, but it may be a good idea to see what is happening in a packet capture.

 

[daniel.hayman]

Hi NickD_3cx,

Thanks for getting back to me.

I've been troubleshooting for a short while now and am unsure now as to whether this is a specific phone issue as I have seen teh issue on some Yealinks T21s.

When I originally posted I had configured the phones to use a STUN server. I have now tried using the Session Border Controller. With this is use I am unable to make any sort of transfer attended or un-attended. I am even unabel to transfer *777 echo test calls from phone to phone. Prior to any attempt at transferring *777 the echo service works as expected.

Any help would be gratefully received!

Thanks
Dan

 

[NickD_3CX]

The only thing I could suggest is you doing a capture and see what the Draytek phones are doing during the transfer, then compare that to a working set of phones. Then once you identify the difference in behavior, see if you can somehow configure the Draytek phones to 'behave' differently.
Sorry, I realize this is a bit vague, but as I said, I have no experience with these phones so I cannot be more specific.

Generally this is the reason why 3CX has 'supported phones', because some don't work out of the box...

 

[daniel.hayman]

Hi Nick_3CX,

I've managed to capture an unsuccessful call transfer with wireshark. I've taken a look in wireshark and part from a phone call with feedback (both phones on speaker phone!) I can only see a 407 proxy authentication.

If you have the time it would be great if you're able to take a look. I am hoping to use some supported phones this afternoon and will let you know the results.

Thanks
Dan

 

[daniel.hayman]

Hello,

I managed to capture a couple more sessions.

I have a successful Yealink transfer and also a successful un-attended Draytek transfer and in the same session an unsuccessful attended transfer.

If anyone has the time to help it would be ace!

Thanks
Dan

 

[NickD_3CX]

From what I can see in the captures, if I understand the setup correctly, they Draytek phones don't even seem to be sending a REFER message if the second call has been answered.

Now in the second capture I also found a call where the completed the attended transfer before the extension you were transferring to had answered (Semi-Attended Transfer), and in that case, it did seem to send a REFER message but the receiving party seemed not to like this...

 

[fistameeny]

Hi,
Sorry to dredge up an old thread, but I'm trialling 3CX with a bunch of Draytek 350 phones and I'm experiencing exactly the same. A call transfer from phone to phone results in the caller being left on hold, and the phones showing their status as "busy" until I restart 3CX.

Did you manage to get 3CX working with your Draytek phones?