Question: How to read a file in extensions `Asterisk 13` and `OpenWRT 17.04`? For example, I'd like to resend the text from the file to chat. The application `ReadFile()` is missing in the repository, unfortunately.

Answer: 
ReadFile has been deprecated. According to documentatin you should use the FILE function instead.

FILE function syntax:

```
Set(varname=${FILE(file,0,length)})

```

Instead of Readfile Application:

```
ReadFile(varname=file,[length])

```

Source: [Asterisk Project Documentation](https://wiki.asterisk.org/wiki/display/AST/Asterisk+11+Application_ReadFile)
You have 2 options

1) Use AGI and bash(php, python etc) script to read parts of file you need. 

2) Build more modules (see openwrt doc, quite easy).