Some operators only support package activation via dial codes, such as *61#, ##002#, *134*355#, etc. These codes can be used to set up outgoing voice and data calls and some other supplementary services. For example, this can be used order paid services like additional mobile data for your SIM card.
RUTxxx routers can execute these codes (with the exception of voice calls) with the gsmctl -A 'ATD<dial_code>' command. The command can be executed via a command line interface (CLI) like the CLI built-in to RUTxxx routers' WebUI or via SSH. For example, if you want to execute the dialling code *134*355#, the command to do this would look like this:
gsmctl -A 'ATD*134*355#'
This is both similar and different to using the Dialling number to establish a PPP data connection. It uses the same command, but the purpose is different: the Dialling number is used whenever the PPP connection is restarted (e.g., after router reboot or modem restart) with the sole purpose of re-establishing the data connection. So you can't really use it to easily execute various types of dialling codes at any point in time.