11 files declare their use of SmsMessage in SMS Framework 8

Incoming.php in tests/modules/sms_test_gateway/src/Plugin/SmsGateway/Incoming.php

PhoneNumberVerification.php in src/Provider/PhoneNumberVerification.php

SmsBlastForm.php in modules/sms_blast/src/SmsBlastForm.php

SmsFrameworkDeliveryReportUpdateTest.php in tests/src/Kernel/SmsFrameworkDeliveryReportUpdateTest.php

SmsFrameworkMessageEntityTest.php in tests/src/Kernel/SmsFrameworkMessageEntityTest.php

SmsFrameworkPhoneNumberProviderTest.php in tests/src/Kernel/SmsFrameworkPhoneNumberProviderTest.php

SmsFrameworkProviderTest.php in tests/src/Kernel/SmsFrameworkProviderTest.php

SmsFrameworkSmsSendTest.php in tests/src/Kernel/SmsFrameworkSmsSendTest.php

SmsFrameworkTestTrait.php in tests/src/Functional/SmsFrameworkTestTrait.php

SmsFrameworkTokenTest.php in tests/src/Kernel/SmsFrameworkTokenTest.php

SmsMessageTest.php in tests/src/Unit/Message/SmsMessageTest.php