how to update mobile number for customer using function module sd_customer_maintain_all???

Hi ,

      i am trying to create a customer using SD_CUSTOMER_MAINTAIN_ALL.

      the problem is i need a field to pass mobile number into the FM for customer.

    as of now i passing the telephone number and mobile number in telf1 and telf2 respectively in kna1 table for FM.

   if i check in xd03 it is not updating in mobile field.

  so i want a field name to pass the mobile number in FM SD_CUSTOMER_MAINTAIN_ALL.

OR ANY OTHER WAY TO after creating the customer to update mobile number to the customer.