Nokia Asha 303 - What does the indicator 1 or 2 on my call display mean?

The number indicates the active phone line. This indicator is shown only if the SIM card supports two subscriber numbers, that is, two phone lines.

Press and hold # to select Line 1 or Line 2 for making calls and sending text messages, you see a prompt Change the phone line if you have subscribed to this service. When the first line is selected, indicator 1 is shown in the standby mode.

When you remove the SIM card, the number indicator disappears from the display.