Can I do 3-way calling with the LineLink device? I have the little home voip box from T-Mobile and I can receive an inbound call, press "flash" on my phone, and make another phone call. I can then flash back and forth between the two calls. I just don't know how to join the second call back to my first call to make a conference call.
I don't see why you wouldn't be able to but there may be additional charges.
LineLink does support 3-way calling or conference calling. You'll just need a phone that supports it. To find steps to conference call or 3-way call, you'll want to refer back to the manufacturer of the phone. Luckily, they usually have this helpful info on their site.