International Numbering Plans is specialised in world-wide (tele)communications related numbering plans, and offers a range of on-line services for a variety of market segments in the global telecommunications sector. Most on-line services are free of charge for personal or limited use. For professional and business use various subscriptions are available.
The International Mobile Equipment Identity or IMEI is a number unique to every GSM and WCDMA and iDEN mobile phone as well as some satellite phones. It is usually found printed on the phone underneath the battery. It can be found by typing *#06# on a handset. (Source – Wikiepedia)