Angelc19,
I'm Sam and I own CircleNet and I'll try and answer your questions here.
We do support faxing Via T.38, if you have a stable internet connection without jitter/ packet loss it is stable it works well. If your faxing from your device now with VestaLink it should work with us to.
If your talking about a web based faxing service or a fax2email service that we don't offer.
I would be willing to try and port your number to our service free of charge. I can't promise we can get it but if we can't your not out anything.
If I am successful and you like are service you can stay, if not you can port over to Anveo or another provider of your choice..
BTW I'm not all of CircleNet but I'm 50%, the better half is my wife Angela who's much more of an introvert than I.
Thanks!
Sam