Different queries inserting same mobile number?

I am currently running these queries:

INSERT INTO `action_4_members` (campaign_id, mobile, join_txt, join_txt_date, additional_txt, additional_txt_date, misc_data) VALUES ('15', '6421315710', 'offprem', '2009-12-11 19:32:58', '762355', '2009-12-11 19:33:35', '')
INSERT INTO `action_4_members` (campaign_id, mobile, join_txt, join_txt_date, additional_txt, additional_txt_date, misc_data) VALUES ('15', '6421816249', 'offprem 239851', '2009-12-12 08:48:16', '239851', '2009-12-12 08:48:44', '')
INSERT INTO `action_4_members` (campaign_id, mobile, join_txt, join_txt_date, additional_txt, additional_txt_date, misc_data) VALUES ('15', '64211044428', 'offprem', '2010-01-21 13:44:05', '703352', '2010-01-21 13:45:06', '')
INSERT INTO `action_4_members` (campaign_id, mobile, join_txt, join_txt_date, additional_txt, additional_txt_date, misc_data) VALUES ('15', '64272839305', 'offprem', '2010-01-22 10:20:18', '804662', '2010-01-22 10:21:22', '')
INSERT INTO `action_4_members` (campaign_id, mobile, join_txt, join_txt_date, additional_txt, additional_txt_date, misc_data) VALUES ('15', '6421650691', 'offprem', '2010-01-22 11:16:47', '721646', '2010-01-22 11:18:07', '')
INSERT INTO `action_4_members` (campaign_id, mobile, join_txt, join_txt_date, additional_txt, additional_txt_date, misc_data) VALUES ('15', '6421776525', 'offprem', '2010-01-22 12:32:37', '202725', '2010-01-22 12:33:56', '')
INSERT INTO `action_4_members` (campaign_id, mobile, join_txt, join_txt_date, additional_txt, additional_txt_date, misc_data) VALUES ('15', '6421538186', 'offprem', '2010-01-25 16:02:40', '214013', '2010-01-25 16:03:15', '')
INSERT INTO `action_4_members` (campaign_id, mobile, join_txt, join_txt_date, additional_txt, additional_txt_date, misc_data) VALUES ('15', '64211663262', 'offprem', '2010-01-26 15:55:36', '210310', '2010-01-26 15:57:07', '')
INSERT INTO `action_4_members` (campaign_id, mobile, join_txt, join_txt_date, additional_txt, additional_txt_date, misc_data) VALUES ('15', '', 'offprem', '2010-01-27 16:03:22', '', '', '')
INSERT INTO `action_4_members` (campaign_id, mobile, join_txt, join_txt_date, additional_txt, additional_txt_date, misc_data) VALUES ('15', '64212726456', 'offprem', '2010-01-29 20:20:16', '206262', '2010-01-29 20:21:42', '')
INSERT INTO `action_4_members` (campaign_id, mobile, join_txt, join_txt_date, additional_txt, additional_txt_date, misc_data) VALUES ('15', '64272093834', 'offprem', '2010-01-30 15:14:45', '868237', '2010-01-30 15:15:43', '')
INSERT INTO `action_4_members` (campaign_id, mobile, join_txt, join_txt_date, additional_txt, additional_txt_date, misc_data) VALUES ('15', '64212021054', 'offprem', '2010-02-02 15:04:07', '204479', '2010-02-02 15:05:02', '')
INSERT INTO `action_开发者_开发百科4_members` (campaign_id, mobile, join_txt, join_txt_date, additional_txt, additional_txt_date, misc_data) VALUES ('15', '64212776175', 'offprem', '2010-02-02 17:27:14', '222380', '2010-02-02 17:28:25', '')
INSERT INTO `action_4_members` (campaign_id, mobile, join_txt, join_txt_date, additional_txt, additional_txt_date, misc_data) VALUES ('15', '64211428506', 'offprem', '2010-02-26 13:13:23', '245767', '2010-02-26 13:14:33', '')
INSERT INTO `action_4_members` (campaign_id, mobile, join_txt, join_txt_date, additional_txt, additional_txt_date, misc_data) VALUES ('15', '', 'offprem 230777', '2010-04-13 09:55:17', '', '', '')

and as you can see the mobile number is different in each query, however it seems to be always inserting the same mobile number: 2147483647

why would it be doing this?

Probably your "mobile" table field is 32-bit integer and the phone numbers are overflow, change "mobile" field to VARCHAR(12) or something similar. 2147483648 is maximum signed integer value for 32-bit systems.