The 'call transfer' functions described in the V6 call control API guide (these include call_hold, call_reconnect, call_enquiry and call_transfer) are only supported if you are running one of the following protocols;
- Euro ISDN
- DPNSS (with the -fTR switch enabled)
If you are running one of these protocols and the call transfer functions are still not working, check the following:
Look in the V6 call control API guide and turn to the section entitled 'call transfer'. The section describes what supplementary services your exchange has to support in order for call transfer to work. If you are unsure whether or not your exchange supports these services, you should contact them and find out.
If you are running Euro ISDN, check that you are downloading Aculab firmware that supports these call transfer functions.