asterisk users - Oct 2007 - Long duration calls with Asterisk out to VoIP telco

Hi list,

My long duration calls are being timeout by my SIP VoIP provider for
failure of receiving re-INVITE within their timeout limit. Is there a
way to config Asterisk to automatically send a re-INVITE message every
10 to 15 minutes? I looked into the sip.conf file and couldn't find such
a parameter. Thnx.