SOAP::Lite will send things that look like numbers as numbers, even if you want them to be sent as strings. If you want them sent as some other datatype, you'll need to use SOAP::Data:

!/usr/bin/perl --
use SOAP::Lite; 
my $var1=1234; 
my $var2=3456; 
my $accno = SOAP::Data->type( string => $var1 ); 
my $pinno = SOAP::Data->type( string => $var2 ); 
my $ret= SOAP::Lite
  ->proxy('http://192.168.0.107:8080/ws4ee/services/BankingService?wsd
+l')
  ->loginUser($accno,$pinno)
  ->result;
[download]

If this isn't what the problem was (it was a little unclear from your description, but I know this is a common problem with SOAP::Lite), please explain what you expected, and what you actually received (including error messages, etc.)