This is a simple VOIP API manipulation.
a - locate a VOIP service on the web, that can initiate international phonecalls & SMS
b - payment for the web service should be per use and not monthly
c - build a small server script that will get a web request and activate the VOIP API
web request should be restricted by password (password will kept in separate file on server)
d - samples for request
1 - send sms text: "hell world" to +207-341-6652
2 - initiate a call to +207-341-6652 for 10 rings (or seconds)
3 - create a conference call numbers: +207-341-6652, +207-341-6633
Please bid only if you made some preliminary tests and already know with which of the VOIP services you will work.
Time: up to 3 days
Budget: up to 30$