(519) 763-5000 is the local access number in Guelph for Distributel.  If a person uses Distributel as their LD provider, they dial this number to access the system and call other people.  On the receiving end of things, you will see this number whenever anyone using Distributel calls you using the Distributel LD service if you are in the Guelph area.  In Toronto, you would see (416) 969-5000, in Ottawa (613) 237-7000, and so on.  As for the dial-tone on call-back, that's how their system works.  When a subscriber dials the local access number it rings through to the system and gives them a 2nd dial-tone at which time they enter the desired LD number.

Some angry lady called me and this number showed up. She said I have been calling her repeatedly but i havn't made a single call for days and my phone has been off.

(519) 763-5000 is the local access number in Guelph for Distributel.  If a person uses Distributel as their LD provider, they dial this number to access the system and call other people.  On the receiving end of things, you will see this number whenever anyone using Distributel calls you using the Distributel LD service if you are in the Guelph area.  In Toronto, you would see (416) 969-5000, in Ottawa (613) 237-7000, and so on.  

As for the dial-tone on call-back, that's how their system works.  When a subscriber dials the local access number it rings through to the system and gives them a 2nd dial-tone at which time they enter the desired LD number.

Received this call tonight...did not pick up, did not leave a message. Ontario 9:10 pm

I think this comes up when someone calls from Toronto using a calling card

on sunday feb.1.2009 @ 3:13pm someone called my cell phone, as soon as i answered my phone the person hung up. when i called back all i got was a dial tone.