What is the difference between a phone number and a SIM card number?

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While often used interchangeably in everyday conversation, a phone number and a SIM card number are distinct identifiers that serve different purposes within the mobile telecommunications ecosystem. They are related, but not the same, and understanding their individual roles is crucial.

Phone Number (MSISDN - Mobile Station azerbaijan number database International Subscriber Directory Number)
Your phone number is the sequence of digits that other people dial to reach you on your mobile phone. It's the public "address" associated with your mobile line, allowing you to make and receive calls and send/receive text messages.

Purpose: To enable communication (voice calls, SMS) to and from a specific subscriber. It's what you share with friends, family, and businesses.
Format: It follows the hierarchical structure discussed earlier (country code + area/network code + local subscriber number), adhering to the E.164 standard. For example, a Bangladeshi mobile number might be +880 1712 345678.
Portability: Critically, your phone number is not permanently tied to a specific SIM card. Through a process called number portability, you can keep your existing phone number even if you switch mobile network operators (e.g., from Grameenphone to Robi) or get a new SIM card from your current operator (e.g., if your old SIM is lost or damaged). The network simply re-associates your existing number with your new SIM card.
Assignment: The phone number is assigned by your mobile network operator.
What it identifies: It identifies your subscription to the mobile network service.
SIM Card Number (ICCID - Integrated Circuit Card Identifier)
The SIM card number, more formally known as the ICCID (Integrated Circuit Card Identifier), is a unique serial number assigned to the physical SIM card itself. A SIM (Subscriber Identity Module) card is a small, removable chip that you insert into your mobile phone. It acts as your identity on the mobile network.

Purpose: To uniquely identify the physical SIM card hardware. It's like the serial number of the chip. It helps the mobile network authenticate