Issues with special characters and dial-in

[simoncolincap]

Describe the bug We're using Scalelite for telephone dial-in and it works great, we just had some issues during setup because of phone numbers with the country code written as +49 instead of 0049. These numbers get used as from-user by our SIP provider and this leads to errors in the dialplan files since the + isn't escaped in the regex. As a workaround we mounted updated templates into the Scalelite Docker container that escaped special characters but it would be nice if this was in the container by default. The + also caused the phone number masking regex to not work, maybe the regex could be controlled by an env? I can write a PR for this if no one else has time to look at this.

To Reproduce Try to setup dial-in with a SIP Provider that has special characters in its from-user. Deployment:

1. Deployment: docker-compose
2. Versions: Scalelite 1.4.2, Freeswitch v1.10.9, BBB 2.6.6
3. Tools used for reproducing the issue: BBB meetings started with Greenlight

Steps to reproduce the behavior:

1. Register Freeswitch with the SIP provider
2. Start a BBB meeting
3. Try to call into the meeting
4. It doesn't work, Freeswitch logs errors about a missing character to repeat because the regex starts with '+'

Expected behavior Dial-in works.