The manual at https://wiki.mikrotik.com/wiki/Manual:T ... D_messages shows how to send a USSD message, and this works:

/tool/sms/send lte1 phone-number="*136*1#" type=ussd

I get a response inviting me to continue the conversation by sending "1".

How do I sent the "1" using the /tool/sms/send tool? Docs don't confirm this.