This excerpt taken from the VZ 10-K filed Feb 28, 2008.
Zero-Coupon Convertible Notes
The previously issued $5.4 billion zero-coupon convertible notes due 2021, which resulted in gross proceeds of approximately $3 billion, were redeemable at the option of the holders on May 15th in each of the years 2004, 2006, 2011 and 2016. On May 15, 2004, $3,292 million of principal amount of the notes ($1,984 million after unamortized discount) were redeemed. On May 15, 2006, we redeemed the remaining $1,375 million accreted principal of the remaining outstanding zero-coupon convertible principal. The total payment on the date of redemption was $1,377 million.