Cisco now spells out that it can pass your personal data — including the fact that you agreed to receive texts — to outside companies that help deliver those messages, and the list is open-ended ("including but not limited to"). This is normal behind-the-scenes plumbing for sending texts, and the same section limits it to running the campaign you signed up for, so the added risk is small. Note the wording is a bit confusing: one sentence says your opt-in status may be shared with delivery vendors, while the next says opt-in and consent data will not be shared with any third parties.
“We may share your Personal Data, including your SMS opt-in or consent status, with third parties that help us provide our messaging services, including but not limited to platform providers, phone companies, and any other vendors who assist us in the delivery of text messages.”
What you can do — If you don't want your number passed to messaging vendors, don't opt in to Cisco SMS campaigns, or text STOP to any Cisco message to end them.