Transferring from an external trunk

I’m using Asterisk 1.4 and FreePBX 1.4, and I have Find Me/Follow Me set up on an extension to ring both my SIP phone and my cell. I want to be able to use Asterisk’s blind transfer feature to transfer calls from my cell to another SIP phone connected to Asterisk. I can transfer from my SIP phone fine, but I can’t seem to get Asterisk to accept the blind transfer code (##) from my cell… Help would be greatly appreciated.