The service offered by telephone companies allowing creating the telephone numbers on the same line where the existing number is. The call tone for every number will be different from another. There is also an opportunity to program a custom ring tone for the incoming call.
Hosted PBX service provider in Canada.
http://pbx.tieus.com
Only $16.95/mo, unlimited calling to 20 major Canada Cities.
unlimited calling for your cell phone
http://www.magicnumber.ca