+1(514) 937-9445 or Toll-free (Canada & US) +1 (888) 947-9445
Just do your best. Do not omit a unit of time because you don't remember the address. Instead, just get the times as close as possible, and explain whenever you don't know something.
On my form I lived for one year at a place in rural China that did not have an address - so I described where the house was. There were no phones there then, so I explained that. I also had no idea what any of my addresses were when I lived in South Korea, so just explained that. There was never any issue with this with the visa officer.
 

Hi to all,

I just want to update you guys that even if i made a few mistakes in answering the form, they still approved me as a sponsor, I checked my ECAS and it was DM last May 7,2011... After a months of worry i can relax now. Thank you guys for a good advise that i received here... :)
 
you are welcome and good luck with the remaining process

DNT2003