1) Welcome to the Party!
2) As you are obviously new here, I have some suggestions to help us all help you:
When you post, please post your entire configuration including (but not limited to) your installation method and vicidial version with build.
This IS a requirement for posting along with reading the stickies (at the top of each forum) and the manager's manual (available on EFLO.net, both free and paid versions)
You should also post: Asterisk version, telephony hardware (model number is helpful here), cluster information if you have one, and whether any other software is installed in the box. If your installation method is "from scratch" you must post your operating system and should also post the .iso version from which you installed your original operating system. If your installation is "Hosted" list the site name of the host.
If this is a "Cloud" or "Virtual" server, please note the technology involved along with the version of that techology (ie: VMware Server Version 2.0.2). If it is not, merely stating the Motherboard model # and CPU would be helpful.
Similar to This:
Vicibox X.X from .iso | Vicidial X.X.X-XXX Build XXXXXX-XXXX | Asterisk X.X.X | Single Server | No Digium/Sangoma Hardware | No Extra Software After Installation | Intel DG35EC | Core2Quad Q6600
3) A sip trunk is a sip trunk. They rarely stray or differ much. If you have an existing one, you can likely copy it for the twilio one. Note that very few sip carriers understand the idiosyncrasies of Vicidial, so they'll give you generic asterisk information that does not quite work, but DOES contain the necessary information for it to work in Vicidial.
4) That being said: Since this is about a sip carrier, and you have not posted any of the sip carrier information (change user/pass/IP to "X's" where they occur) ... we really can't tell you what is wrong.