I have a group of phone lines that are connected to a centrex trunk, managed by the telecom provider. This is not our phone system and is not managed in any of our equipment. My alarm lines are outside of the trunks but cost me more. Essentially, the more lines in the trunk the cheaper it is for me. Is it permissible by NFPA 72 to use a phone line connected to a centrex trunk? Lines connected to the trunk receive dial tone and can dial any number within the trunk without a prefix. Any number outside of the trunk, which would include the monitoring station, requires a prefix, 5, to dial. No pause is required.
The fire panels we have now all dial a local monitoring station. If the number was (123) 456-7890 then in the centrex trunk version it would be just like dialing a long distance number except a 5 instead of 1. Ex. 51234567890.
If it is permissible can someone direct me to the document that states that? If we enact the change I want to have documentation so my fire alarm installers have it.