Android :: Unable To Update Contact Phone Number

I am currently unable to update an existing contact record's phone number. I am able to insert a new phone number to an existing contact record but unable to delete or modify existing phone number records of a contact. Is there a way to either: - delete an existing phone number from a contact record. or - update an existing phone number of a contact record.

The sample code is as shown below:
To delete existing phone numbers of a contact record: row = getContentResolver().delete(ContentUris.withAppendedId (Phones.CONTENT_URI, uid),null,null);
Log.v(TAG,"row =" + row);

The row value is always 0 even if phone numbers are present. Thus, the deletion does not take place. To update a phone number:
Uri PersonUri = ContentUris.withAppendedId(People.CONTENT_URI, uid);
Uri PhoneUri = Uri.withAppendedPath (PersonUri,People.Phones.CONTENT_DIRECTORY);
ContentValues values = new ContentValues();
values.put(Phones.NUMBER,"1234567890");
values.put(Phones.TYPE,1);
row = getContentResolver().update(PhoneUri,values, null, null);

This throws a unsupported Operation exception.