Maple Aircraft has issued a 6.00% convertible subordinated debenture due 2023. The conversion price is $64.00 and the debenture is callable at 104.00% of face value. The market price of the convertible is 89.25% of face value, and the price of the common is $58.50. Assume that the value of the bond in the absence of a conversion feature is about 63.25% of face value. Assume a face value of $1,000. For the remaining questions, assume the conversion price is $64.00 as stated in the original problem. Required:
When should Maple call the debenture?