Not sure if this exactly responds your question, but voice and message applications (eg if you receive an incoming call or SMS message) usually cause the running
Java Midlet(s) to go to suspended state.
Midlets have lower priority in a phone and you can't change
that setting (at least in a platform independent way).
All that you can control is your own application behaviour regarding
Wireless Messaging API connections, but then only if you want to create them.
[ March 28, 2006: Message edited by: Eduardo Marques ]