[andy]

For networks themselves, it does seem to be a mainly American and Canadian facility.

There are independent services doing this, but chargeable at typically 15 or 20 cents each. A Google search will find a selection, some with a free trial

Other firms allow sending from a webpage, or have mobile Java clients, or both. Vyke is 2 cents a message. The Betamax VoIP brands sometimes have free message promotions, but switch from time to time and there's a slightly unknown or movable fair use policy on the free ones