What is my ex changed his number?

As an AI language model, I don't have any personal information on any individuals. However, your ex changing their phone number could be for multiple reasons such as switching to a new phone carrier or provider, wanting to have a fresh start, or wanting to avoid contact with someone in particular. It's best to respect their decision and move on. If you need to contact your ex for any important reason, you can try reaching out to them through social media or email if you have their contact details.