<ESC> equivalent in C#

Question

I have been working on an API provided by Zeacom for making IVR calls from our system. We are using this API in our C# code. Most of the features are working as expected.

There are few control sequences I am not able to get it to work. As per the documentation, All the control sequences follow this general syntax notation:

• <ESC> \ <parameter> = <value> \
• <ESC> normally represents the escape character \x1B (decimal 27) that generates the ASCII character 27 (Hex 1B).

The use of the escape character \x1B can be supplemented with a user-defined control sequence using the escape_sequence parameter in the Vocalizer configuration file. This is particularly helpful for using native control sequences within SSML or other XML documents because the escape character \x1B is not permitted within XML documents For example His name is <ESC>\pause=300\ Michael

Following are the things I tried:

1. Used <ESC>. The system instead of treating it as escape it read it as Less than escape and greater than or something like that.

2. I added Microsoft.VisualBasic namespace and

   tts_obj.sText = Strings.Chr(27) + "\\vol=80 \\ " + "I am at 80 Volume ";
   tts_obj.sText += Strings.Chr(27) + "\\vol=90 \\ " + "I am at 90 Volume ";
   tts_obj.sText += Strings.Chr(27) + "\\vol=100 \\ " + "I am at 100 Volume ";
   

   This wasn't of any help too.

Any idea how to get this escape character to work in C#?
Any kind of help greatly appreciated.