Some phone codes....I don't know if these work overseas....

*57: Call Trace
This is a lets you find out the most recent number that has called you.
To use: dial *57

*77: Anonymous Call Rejection
If someone is attempting to call you and their caller ID is blocked, you can stop them from calling unless they unblock their number. It's also useful if you are going to call someone on a phone that may have the feature turned on.
To turn on feature: dial *77
To turn off the feature: dial *87

*67: Block an outgoing call
You may want to block the number you are calling from. Dialing *67, then the number will allow you to do that for one phone call. It's very useful if you want to call up someone and chew their ass out.
To use: dial *67 000-000-0000

*02 DeActivate *66 Notification on Busy Signal
*03 DeActivate *66 Notification (One Time Only)
*12 Call Assitance (Police)
*30 Cancel Forwarding
*31 Automatic Forwarding
*32 Notify
*40 change forward-to number for customer programmable call forwarding busy-line
*41 six-way conference calling activation
*42 change forward-to number for customer programmable call forwarding don't answer
*43 drop last member of six-way conference call
*46 french voice activated network control
*47 override feature authorization
*48 override do not disturb
*49 - disable long distance special ring
*51 Intercom Ring I
*52 Intercom Ring II
*53 Intercom Ring III
*54 Extension Hold
*57 Call Trace
*60 Call Screen (Selective Call Rejection)
*61 Selective Distinct Alert
*62 Selective Call Acceptance
*63 Selective Call Forwarding
*65 ICLID Activation
*66 Busy Call Return
*67 Call Display Block
*68 Computer Access restriction
*69 Last Call Return
*70 Call Waiting Disable (Per Call)
*71 Three-way calling (Per Call)
*72 Activate Call Forwarding
*73 DeActivate Call Forwarding
*74 Speed Dialling (8 numbers)
*75 Speed Dialling (30 numbers)
*77 Anonymous Call Rejection
*80 Call Screen Disable
*81 Selective Distinct Disable
*82 Selective Acceptance Disable
*83 Selective Forwarding Disable
*85 ICLID Disable
*86 DeActivate Busy Call Return
*87 Cancel Anonymous Call Rejection
*89 DeActivate Last Call Return
*90 Re-Activate Call Forwarding Busy
*91 De-Activate Call Forwarding Busy
*92 Re-Activate Forwarding No Answer
*93 Call Forwarding No Answer (*91,*93 to completely disable)
*94 Ring Control (Call Answer)
*95 Message Monitor (Call Answer (link|flash) to interuppt/talk))
*97 check if you have messages, remotely (on=2beeps,off=4beeps)
*98 Call Answer