I can't imagine a way to suspend the ftp session and restore it later, but you can execute local shell commands from the ftp session itself. Example:
Code:
ftp -n ftp.something.somewhere <<-EOF
user username password
ls
!ls $HOME
bye
EOF
Notice the exclamation mark at the beginning of the line in red. It tells ftp to execute the command in the local shell. Shell substitutions will be performed as usual before the whole block of ftp code is executed. Hope this helps.