Of course, this may be a test of whether you can read a specification.

• CSV doesn't really do fixed length fields... or do the field widths given imply that some data validation is required ? If so, how should errors be dealt with ?
• The Date/Time fields don't specify the form of the time-stamp -- which makes this part deeply tricky.
• The length of call calculation: if the time-stamps give fractional seconds, what rounding should this perform ?

Beyond that... as a programming language Perl is a little odd, but not that difficult to get to grips with. Some experience with a scripting language will help. You've been offered a number of pointers.

However, a key thing about Perl is the free availability of a shed-load of useful stuff you can use. In this case, parsing CSV can be trickier than it looks. But a quick poke at CPAN http://search.cpan.org/ throws up lots of possible helper modules. Now, the tricky bit is deciding which to use... there you might find the excellent monks more inclined to share experience -- assuming you checked the FAQ, Tutorials and searched for earlier discussion(s).