Your problem is that you are using exec in the single-argument form, which is a HUGE SECURITY PROBLEM, not to mention that it will have major consequences to your system if your log file contains legitimate commands following a semi-colon. Here is your code:

exec("call_sms_zh.pl -msg=$_");
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If we expand $_ to include that line of data, your command expands to this:

exec("call_sms_zh.pl -msg=[Thu Jan  4 07:01:27 2001  1327]ln4p47dbs:Gl
+obal_One:new_regext:CRITICAL:Call x84240 Unable to put file; /global1
+/Global120010103.DAT_tmp");
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Note the presence of shell metacharacters (specifically, the semi-colon and brackets). The solution is to clean up your exec call:

exec("/path/to/call_sms_zh.pl", "-msg=$_") or die "exec: $!";
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This form does not pass your string through any sort of shell, so meta-characters in this fashion are "safe", unless call_sms_zh.pl itself uses them in an unsafe fashion, in which case you're screwed again and need to fix that other script.

If you're using call_sms_zh.pl in a number of scripts, you might be better off turning this Perl script into a real Perl module, and just use that module from within your other scripts. Going a step further, I think there are modules out there in existence for interacting with SMS services, so that might be another option to pursue.