Richard,
How do you connect from a Hotel pbx phone to Voxalot? Are you calling one of the local PSTN gateways? Even if you can call a a Voxalot number this way, Voxalot does not have Call-Thru. You will not have a way to jump-off Voxolat by using a speed dial or any other way of outbound calling.
Now, if what you have is a Voxalot number that is registered as a trunk in PBXes and you have created a Call Thru system. Then it is PBXes handling the codes once you get the second dial tone than can be used to place a call via Voxalot. PBXes seems to have reserved * for their own calling features so you can't use them to dial a Voxalot speed dia.