I have been using phone card from himtel since past 2 years to call nepal, I was also suffered same issue as discribed by rodiohead, so I have contact to the customer support regarding this issue they suggest me to use their authorized card himtel premium. I thought let also try this one..... amazingly there was no lose of any minutes........clear sound and connection. Now, I have been using himtel's rechargeable phone card 'Himtel Premium' since past one year, I never lost any minutes in this card...... love it.....