sip_session: do not print the numpad if there's no audio

darcs-hash:20090330154112-b2873-91b4cab3b760d43c36f406894b5a041db35b7fa9
clients.console: minor fix in recv_char()

darcs-hash:20090330154354-b2873-676962917fa33b75cd9320fc0e7ac7245032d1f1