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Home » Kerio User Forums » Kerio Operator » Call parking collisions (Calls become orphaned if the parking transfer fails)
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blswjames

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The equipment:
Kerio Operator 2.1.3.
Snom 821 phones, with firmware version 8.7.4.7, auto-provisioned by KO

The scenario:
1) Call A is answered, then parked on "101" (prefix setup = '10...', so we have parking slots 100 - 109 to use)

2) Call B is answered, then tries to park on "101" (where call A is still parked.)

3) Snom phone gives error saying "Transfer failed".

4) At this point, Call B is now in limbo, neither transferred nor on hold per se. Trying to park on any other slot at this point just gives the same error. Trying to rejoin the call is impossible. The only way out is for the caller to hang up and start over.

I can't tell if this is a Snom issue or a Kerio issue, but I am thinking it's more likely to be caused by Operator's call parking feature. Since the user has to pick the parking slot, there is always a possibility that they will try one that is already in use. Is there a way to have it either auto park to the next available slot instead, or at least allow me to try again?

Is there a work-around I can use in the mean time? Any others out there using KO with Snom phones and call parking? How do you get around this issue? The customer is relying on the parking feature and won't let us proceed until this gets solved.

Thanks!
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Filip Jenicek (Kerio)

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Hi,

The situation is quite complicated and depends on the device you use, when a transfer was initiated, and the type of transfer (attended/blind).

Luckily, I have been able to reproduce it on the new snom 710 and 870 phones. It appears that the they use a SIP REFER transfer which doesn't work well with call parking in Operator.

Before I investigate the situation and come up with a solid solution, there are few workarounds:
1. Place a call on hold before doing the transfer. Press [hold], dial a number, and press [xfer].
2. Configure the snom phone to "Disable blind transfer (REFER) = yes". The option can be found on the "Advanced - SIP/RTP" screen.

Filip

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Filip Jenicek (Kerio)

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blswjames wrote on Fri, 02 August 2013 23:32
I can't tell if this is a Snom issue or a Kerio issue, but I am thinking it's more likely to be caused by Operator's call parking feature. Since the user has to pick the parking slot, there is always a possibility that they will try one that is already in use. Is there a way to have it either auto park to the next available slot instead, or at least allow me to try again?


In case the customer uses a 3-digit dialplan you could configure call parking to require three digits and then instruct users to park calls on the same parking position as their phone number.

Automatically parking a call in the next available slot doesn't make sense as you would miss the information which position it is. By default, asterisk solves it by announcing the position via an IVR menu. However we didn't want to go this way and we implemented call parking where one has to choose the position before parking a call.

When you choose an occupied position, depending on the type of the transfer, it either fails or the previously parked call is retrieved and you accidentally bridge two strangers together.

Filip
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blswjames

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Quote:
In case the customer uses a 3-digit dialplan you could configure call parking to require three digits and then instruct users to park calls on the same parking position as their phone number.

Good idea. Avoids collisions by essentially assigning a parking slot per user. That probably will work just fine.


Quote:
1. Place a call on hold before doing the transfer. Press [hold], dial a number, and press [xfer].
2. Configure the snom phone to "Disable blind transfer (REFER) = yes". The option can be found on the "Advanced - SIP/RTP" screen.

I don't think I quite understand the dynamic between blind transfer and attended transfer. It sounds like disabling REFER will force all transfers to be attended, meaning that users would perform the procedure like this:
1) Place caller on hold
2) Call the target (transfer to) extension
3) Press transfer button to join the "held" caller and the target
4) Hang up

Is this correct?

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Filip Jenicek (Kerio)

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Yes, the procedure is correct. I think that when you disable REFER, the xfer button behaves the same way as the hold button.
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