To avoid high roaming call charges, how do I get the Expert to call me on a foreign number or via messenger, whatsapp, line etc?

Unfortunately, the Tax experts are not able to call foreign numbers or use services like Whatsapp to contact you. 

If you know someone who has a Canadian number and can transfer a call to you, you can try having the Tax Expert call that number. Once the Tax Expert has started the screen sharing program with you, you can disconnect the phone call.

Thanks but when I talked with an expert a few days ago we got we started the screen sharing but continued the call.  Please confirm that I can e.g. connect my headphones to laptop and can hear the expert via the screen sharing or can chat to them some other way ?

Yes, once you are connected you should be able to communicate over the laptop.

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