I have one group that I have been texting for a couple of years. All of a sudden it won’t send texts.

1. There are three types of group messages that you might see: group iMessage, group MMS, and group SMS. The Messages app automatically chooses the type of group message to send based on settings, network connection, and carrier plan. For example:
   1. If you and your recipients are using Apple devices and iMessage is turned on, then the group message is sent as an iMessage. If you can't turn on or sign in to iMessage or FaceTime - Apple ... If you can't turn on or sign in to iMessage or FaceTime - Apple ...
   2. If you send a group message to people who are on Android, then the message is sent as an MMS or SMS message. Check if you have an SMS plan enabled by your carrier for the SIM/eSIM that you use on your device. Apple Inc does not provide SMS services. You need to contact your Carrier to enable SMS and/or MMS.
2. To activate iMessage and FaceTime using your Phone number
   1. First, check to know whether you have an SMS plan enabled at least for One SMS*** with your carrier. Contact your Carrier (Cellular Service Provider) the agency that issued the SIM to you
   2. If your iPhone is used with a carrier not found in the wireless carrier articles, make sure you can send and receive international SMS. (One international SMS*** Only)
   3. *** You may not have an SMS plan (Domestic & International) enabled by your carrier for the SIM/eSIM that you use on your device. Apple Inc does not provide SMS services.

If none of the above steps resolve the issue, it is recommended to reach out to Apple Support or visit an authorized service center for further assistance. They can provide specific guidance based on your device model and iOS version.