Sizing a new unit for our business

I am new to this group and am interested in finding out details on the system. We have 350 extensions in two locations covered currently by one phone system connected through a dedicated fiber. Is there a practical limit on the number of extensions handled by the software.

Your primary restrictions are going to be based on the hardware you are utilizing, and your dial plan. Meaning your codec choices, transcoding, call recording options, call queuing or any other processor intensive will impact how many calls you can pass on your hardware. There are of course limits on the number of calls that can be passed by the SIP channel driver, but for installations in the size you are speaking of, the bigger factor will be hardware. Not knowing what hardware you have in place you can take a look at our Certified Appliance Line for comparison, we name them based on the recommended number of extensions.