GAW: If you call a cow and it comes to you that’s a D’Oraisa of M’chamer. That seems like a very apt (see what I did there?) precedent for talking to a phone.
Only because a melacha is being done via your dibbur, as you are chayiv in Shvisas B’hemto. The proposal would have to be voice only on both sides to fully avoid any kisevah.
metrodriver – care to explain why that is relevant, especially as it has already been noted?