I must say as a company you are having a lot of problems with your telephone system.
I did notice in one of the service statement Mand slipped in the info you have a Symposium system. Well just for the record I am a fully qualified Symposium administrator and script writer (and I have the BT certificates to prove it). Sadly now retired.
I had the first Symposium system seen in South Dorset installed at the insurance company where I worked. We had 72 incoming lines and did work for 23 separate companies. The site subsequently became a ‘Show and Demonstration’ site for BT and I took many companies round the site to show them how it worked (and yes I was proud of my site). We had a Meridian 61C, with Symposium handling call distribution, Meridian Mail providing messages and me running the whole show.
The first thing I learnt was, don’t let BT write the scripts, do it in house (I hope you are) and do everything ‘Live’. Next ignore just about everything BT tell you (I hope they are better now but the Symposium engineers were just getting used to the system and had no real idea of how to network computers and voice communications), go to the Nortel website and blag your way into getting access. Get onto the forums there and you will learn so much more.
I was downloading and installing patches for Symposium long before BT had even found they existed, let alone tested them that’s why the system worked so well. I had many problems put down to hardware which turned out to be the software and just needed patching. I still have the lists of error codes (from the Nortel site) and information I was passing on to my local BT engineer, my one and only good (brilliant), contact from BT.
And just for the record the only time Symposium needed re-booting was when the Windows (sic) server threw a wobbly and needed a restart. Although I had a proper air conditioned room with the system in I was also able to run the whole show from my desk (over the LAN) or from my home 20 miles away (over dial up modem) so I just cannot understand why you are having all these problems.