A couple of small caveats. In some countries this mights still be illegal, or it might be illegal if you are acting as an agency and don’t employ the advisers.
Also, it would be unwise to use analogue lines for this. You want to make the PSTN interface using ISDN, either directly or via an ITSP.
A long time ago, all UK PABXes had to block attempts to bridge two PSTN lines.
Currently it is still illegal to bridge a third party call via a GSM gateway to another third party.
The original reasons were maintaining voice quality and monopoly preservation, but current reasons are more likely to be avoiding essentially fixed traffic monopolising air interface base stations and ensuring that governments can obtain communications meta data.
Analogue lines typically have poor support for answer and disconnect supervision and you may have calls staying up until the network timeout is reached.
Thanks David. I’m aware that my envisaged set up is similar in form to adult telephone services, external client (pstn) routed to external employee (pstn). Whilst this is absolutely not my business model, how would they circumvent the issues you note? Surely they would use analogue telephony. Both my clients and employees would likely by based on analogue pstn lines. (I also am aware of “pass the phone” interpreting services accomplishing the same task, external client routed to external translator, though the adult services model is the more obvious example.)
The rules will vary from country to country. I haven’t researched the precise situation in the UK, but at some point you need to become a licensed operator to handle third party traffic. Parts of, say the Middle East, may be much more restrictive.
If your business model is that you em[list=][/list]ploy the experts, but they work from home, I’m pretty sure there is no problem in the UK. If the model is that you provide a clearing house for connecting to freelance experts, in the UK, I would want to research the legal position further to see if you did need some sort of licence, and what meta data you need to maintain to be able to satisfy enquiries from the authorities.
The main caveat about analogue lines is at the Asterisk end. A lot of people try and set up small systems using analogue lines then get caught out because they can’t tell when the call has been answered or the called party has cleared.