I think this is what they mean. Just search on "text signature"  https://www.getapp.com/operations-management-software/digital-signatures/?camp=bing&utm_content=o&utm_source=ps-bing&utm_campaign=COM_US_Desktop_BR-Electronic_Signature&utm_medium=cpc&account_campaign_id=267721459&account_adgroup_id=1178677171470358&ad_id=73667528993557&utm_term=electronic%20signature%20app%20free&matchtype=b&msclkid=6bf8aec843aa103de630f1706aee8041 https://simpletexting.com/text-message-signature-examples/#:~:text=Text%20message%20signatures%20allow%20you%20to%20share%20your,team%20to%20scale%20up%20your%20text%20messaging%20channel.