Have the calls tapered off at all? If not, call & speak to your old boss and tell them you don't want to burn bridges, but your time is valuable; and now that your job is looking for a job, your fee is $100/hour and you bill in 15 minute increments and each phone call will be an invoice for $25. Maybe even type up a quick contract and put a signature line on it and fax it to them. That should stop the calls.
I agree ...
I assume those calling you are your peers not your boss. I do not know your area and line of work, but I suggest not to burn any bridges either
a. scan the calls and ignore them, or
b. as jlima did, helped with a few questions and if the calls not tapered off, called your old boss.

These are the people who can be left high and dry after a layoff.
).
Honestly, this post gave me the first laugh that I have had since the layoff...when I read " forgotten everything you know about your former position"...I LOVE IT !!!! Thank you for a much needed moment of laughter in what is a very stressful time for me and my family ! God Bless!