interprocess communication in OPNET

I am trying to do a simple sort of simulation in which i can get no. of total calls versus blocked calls and no. of trunks available.....
i have made three processors in the node model....first processor is simple_source with custom packet format(packet indicates actually a call)..when ever a packet is arrived from simple_source to processor1...it simply increments total_calls counter and checks whether a trunk is available or not...if it is available it allocates a trunk to call otherwise it increments the counter of blocked_calls...after that processor one sends the packet to processor2 where i want to free the trunk...


now here i have a problem, i want to share the available_trunks counter between two processors......can anybody help me on this....plzzzz

Which version are you using???