Thanks but say all those lines are for separate business activities and you want to answer the call in that particular business name. At the moment you can identify which number (business) they are calling by the 6 buttons, but any more how would you achieve this?
I'm not sure how you set it up like that. As far as I know, Express Talk just uses the next available virtual line to show the next incoming call. Even if you have 2 SIP providers my understanding is if there is no call in progress and someone phones on the second VoIP line, Express Talk should signal the call on virtual line 1. I will say this, I have not done much testing with Express Talk using several VoIP providers at once, but I know that in my set-up Express uses the 'next available' virtual line approach (I'm using ET with Axon though, so it could be a bit different).
I should note that there are other ways to distinguish the call. For example when you use Axon (free for <10 extensions) in conjunction with Express Talk, you can connect an unlimited number of separate VoIP lines and set each one to have their own Caller ID prepend string. This allows you for example to add a 1 in front of line 1 calls, a 2 in front of line 2 calls, etc. When the calls come into Express Talk the Caller ID will be displayed with the Caller ID prepend string to indicate the phone line that was called.
Using Axon also has other advantages, for example you can share the phone lines with more than one Express Talk soft-phone or other compatible VoIP phone. Axon also gives you more power over call routing and can do things like play a music on hold file while callers wait for the call to be answered.