Having Tricom as a backup still won't prevent a dropped call. Also, if I call the client's back on the Tricom phone and they make note of the number, now I will have them returning my calls on that phone and then I'll be dealing with it's $hitty quality too.
Chip, what ExtremeR meant was to have the cheapest Tricom Internet service, to be able to run VOIP (Skype, Lingo, Vonage, etc.) over it. You would just change your "routing" instead of a physical way of "making" the call...
I do not have backup, because there are no backup options here... same as Cobraboy... it's only Codetel.
Fortunately I have clients domestically (in the DR) so they "understand" ...
Another way for you would be to get a US based phone card, where your US-based number would be your access code. Then, dial via Codetel/Tricom/Orange into the US access number and enter your access code. Most likely, the caller-ID would display your access code (your US number) on the called party's phone.