Hi,
I was trying to send sms with (version 1.0) special characters like:
a sum 1+2=3 a division 1/2=0.5 an at @ a tilde ~ and {}

they are not correctly encoded by the bulksms class, i can see in the
gateway history they appear as:
a sum 1+2=3 a division 1/2=0.5 an at @ a tilde ? and ??

I saw you are using the urlencode properities but it's strange because
this function is working properly with the ~ and {}.
So no idea where the bug is!