iRule for LB between few servers and tcp range ports on each server

I need to configure iRule for LB between few servers and tcp range ports on each server

Voip component will send tcp packet (always port 5060) to F5 VIP  F5 will take the tcp5060 and send it to destination servers and change the destination port between range 5040 to 5048 (5040,5042,5044,5046,5048) The return packet should be with the relevant port .

For example :

First packet : voip device --> tcp 5060 --> F5 VIP --> tcp 5040 --> destination server1 Return packet --> tcp5040 Second packet : voip device --> tcp 5060 --> F5 VIP --> tcp 5042 --> destination server 1 Return packet --> tcp5042 Third packet : voip device --> tcp 5060 --> F5 VIP --> tcp 5044  destination server1 Return packet --> tcp5044

And so on till port 5048 .

After finished all ports range on server1 F5 will start the same for server2 .

Please advise how we can do it .

Thanks Shai