How long can one keep a mobile number before switching it to another network?

 There is no set time limit for how long you can keep a mobile number before switching to another network. In most countries, you are free to switch to a different mobile network at any time and take your mobile number with you, as long as the new network is able to support your phone and the mobile number is not locked to your current network.

However, it's important to check with your current network provider about any termination fees, early contract termination fees, or other charges that may apply before switching to a new network. It's also a good idea to verify that your phone is compatible with the new network's technology and frequency bands.