Does anyone know if I can port or use my existing landline phone number to my OBIHAI account?
You would not port a number to ObiHai you would select a VOIP provider open an account and port the number to that account.
Good Luck!
Voip.Ms has free porting still and works well with the Obi.
Your cost per month for them hosting the number is $1 or $1.50 a month.
Google would let you port in for $20 and is free per month to host the number.
Other Voip solutions vary.