Sender ID change may occur when you send messages from a Twilio number that is not local to your recipients, for example using a US Twilio number to send SMS to Polish mobile users. This is often done to comply with local regulations, or to ensure the highest possible delivery rate for your messages.
Sender ID change will not occur when you send messages using a Twilio number from the same country as the recipient, for example using a Polish Twilio number to send SMS to a Polish mobile user.
Sender ID change does not negatively affect delivery quality, however it means that replies from recipients will not be routed back to your Twilio number.
If you need to receive SMS replies from your users, please use a Twilio phone number or short code from the same country as your recipients. This will ensure Sender ID is preserved. For more info, see Receiving Two-Way SMS and MMS Messages with Twilio