I have some accounts to an provider using analog adaptor (SPA2102). I can do a blind transfer by hitting "flash", *98<destination> on an analog phone (*98 is the blind transfer feature code on spa2102). SPA2102 will send something to my provider and initiates the transfer. I can still use my phone after the transfer, so my phone is not tie up while the other 2 parties are on the phone. I would like to replace SPA2102 with a sip trunk which connects directly to my provider. How do I instruct asterisk to send the "something" to my provide to initiate a blind transfer? And what is that something ? Any doco on how this works would be appreciated.