Jitsi Desktop, extra 0 for outside call (sip)

HI

this software is new to me … i installed Jisti desktop, configured as SIP
all working fine, i can call internal / external numbers… be called…

but i want to dial an cellphone, outside number, i need to dial an extra leading 0 for outside calls
can this be configured automaticly ? because everyone has lots of contacts, they are all configured without leading zero, like +32 495 …

thnx in advance