+1(514) 937-9445 or Toll-free (Canada & US) +1 (888) 947-9445
Hopefully this answers your question:

http://www.cic.gc.ca/english/helpcentre/answer.asp?qnum=200&top=17
 
b.arvind87 said:
Thanks ! But can she Apply while she is on a Visitor Visa ?

I think the link answers the question. Additionally, when you look through this forum, you'll find that there have been other cases where people on TRV applied for SOWP.