Seems like a great reason to use the instant-messenger app of your choice (while simultaneously talking on the phone). Instead of reading aloud a couple of lines of code, the customer could paste in the relevant line or two so you could see it for yourself and meditate for a moment. Then you could respond with commands, code patches, or whatever without concern they'd get mangled in the translation. You could converse as this is happening: OK, can you paste in the error message? OK, what's on line 45? Can you try this input sequence? Blah blah blah...
in reply to Debugging Perl over the phone
Of course, from the way you describe the folks controlling things on the other end of the line, it sounds like they might not be amenable to something as <ahem> sophisticated as IMing... it sounds like a pretty bad situation all around, and I sympathize ;-)