Call transfer doesn't work

[TurabG]

Hi,

I have been searching for a proper way of transferring, with no luck. We are using IP phones, call divert and transfer right is granted to extensions. But transfer dial-codes do not work. (*82# and *83#) Which are told to work only on mobile agents. (I don't get the point in dial code for mobiles while they already have transfer keys.)

So how to transfer a call with an IP phone? We have Gigaset C530 which can transfer calls with R key and seems to work, without any dial codes. We also have Vtech phones which have hard transfer keys on them. Pressing the transfer key on this phone, puts the caller on hold (without playing hold music on the caller side, unlike Gigaset), then it offers two options; "Transfer to any party" and "Transfer to base party".

The second option works like intercom and it can transfer the calls if there are any other handsets registered at the same base station. But the first option, which is ment to transfer the call to anyone, including other extensions, says "Not Available" when pressed.

 

[leejor]

There are two types of transfer, attended and unattended. Simple transfer, using a dedicated key, or a single flash, is usually only an unattended transfer, what you seem to be using. To use a dial codes for more advanced features usually requires the set, or ATA to "know" (internal table) what the code is trying to do. In many cases, this is involves a flash, feature code, second dialtone, then additional digits (extension number), then a second flash to complete. Attended transfer usually works this way.

SIP sets can all have different ways of accessing the attended transfer as well. In the case of the Vtech sets, you may be using an internal (set) feature rather than 3CX handling the transfer.

 

[TurabG]

With Gigaset, I can do both attanded and unattanded transfer. Pressing and holding R key puts the caller on hold (with the hold music being played on the caller side) and it asks you to dial the number. If you hang-up the phone, it will be a blind-transfer, a.k.a. unattanded. Or if you wait for the second party to answer, that will be an attanded transfer.

With Vtech, there is already a "Transfer" button, a hard one, right on the phone and it normally allows you to put the caller on hold (oddly without a hold music) and asks you to select from two different options which are "Transfer to anyone" and "Transfer to base". The second option is working just like how Gigaset works. You select another handset, which has another extension registered on the same base, then just like with Gigaset, if you hang up, you will have done an unattended transfer or if you wait for the other party to anwer; it will be attanded.

The problem is, when you select option 1, which is "Transfer to anyone", it immediately says "Not available". If it was the case you told; then the second options wouldn't have worked either. But it transfers the call right as it should do.

As for the dial codes; the manual explicitly states that dial codes do NOT work on IP phones and this comes very much interesting to me. Why not?

 

[leejor]

The transfers appear to be a part of the phones features. You initiate the transfer with the phone, it in turn, activates the transfer with the PBX. You are not interacting with 3CX directly.

You would have to make use of Wireshark to see what SIP messaging is being passed between them, which should tell you why some features are failing.

Star codes (Vertical Services) are usually part of a feature, internal to a device. This is a link to star codes built into Cisco ATA's...https://www.voipmechanic.com/linksys-sipura-star-codes.htm

They are activated after a flash, when you hear the stutter dial tone. The device detects the star as the first character, and "intercepts" the code, then acts on it. Every device can be different, using different codes. The code is interpreted by the device, which then interacts with the SIP server.

 

[TurabG]

By the dial codes I ment the star codes that 3CX supplies; which is already covered in the documentation and which is told to work on mobile agents only. Hence I think it's useless; or I'm missing something here. Because mobile agents would already have soft keys for both attended and unattended transfers; thus they wouldn't ever need hard-to-remember dial codes.

There are also some logs like this in 3CX;

Call or Registration to *88@(Ln.10000@xxxxxxxxxx) has failed.
95.xxxxx replied: 403 Insufficient Credit; from IP:95.xxxxxxx:5060

SIP trunk definitely has enough credits and we are already using it. I don't know what "*88" stands for here; obviously it's not a number we are dialing.

 

[leejor]

The log would seem indicate that you are sending *88 to your provider, which, according to this https://en.wikipedia.org/wiki/Vertical_service_code deactivates all forwarding. (in North America).

On an analogue sip device (ATA), star codes are generally recognised after a flash.

 

[YiannisH_3CX]

I have been searching for a proper way of transferring, with no luck. We are using IP phones, call divert and transfer right is granted to extensions. But transfer dial-codes do not work. (*82# and *83#) Which are told to work only on mobile agents. (I don't get the point in dial code for mobiles while they already have transfer keys.)

Please note that these options do not apply to IP phones and they can only be used for the PBX mobile agent (which does not mean the 3CX clients for mobile devices). These options apply only for calls that are forwarded to a mobile number (GSM) via the "Ring my mobile simultaneously" option.
https://www.3cx.com/docs/pbx-dial-codes/#h.mlp4gmj167pe

Since the devices you are using are not supported by 3CX then we do not control the phones behaviour via provisioning. I would recommend using supported devices to be able to have a predictable behaviour when you are performing a transfer.
https://www.3cx.com/sip-phones/