I don’t believe shell_command supports “alias” in the same way (for example) automations do. The documentation is using the word “alias” as a placeholder for whatever you put in there.
Give the shell command a name (alias) as a variable and set the command you want to execute after the colon. e.g., alias:the shell command you want to execute.
So in your case, your alias is “call_remote”. So you could just have aliases of “service1_call_remote” and “service2_call_remote”, as in: