session/persistence table question

Hi all,

I'm new to iRule and have a session/persist command problem/question. I use a loadbalancer to balance SIP application server. For incoming requests I use the SIP persistence proviel and everything works fine (without using an iRule).

However, it is possible that the application servers initiate a session and all responses have to be routed back to the initiating server. Therefore, I want to add the Call-ID of outgoing invite requests to the persistence table. I generated a VIP on the application server side that uses an iRule to check if the Call-ID of outgoing requests are stored in the persistence table. If a Call-ID is not known, it is inserted together with the application server IP. Here my question: Is it possible to perform such a persistence table manipulation? Afaik, there exists a persistence table for each VIP.

Furthermore, I tried to use the session/persist command to add an IP address to the persistence table. I tried e.g. something like this:

when CLIENT_DATA {
session add uie 123456 [IP::client_addr]
}

(see e.g. http://devcentral.f5.com/Default.aspx?tabid=53&view=topic&forumid=5&postid=1944 )

The syntax check was successfull, but when an UDP Packet arrives, the logs state: TCL error: Rule test - Prerequisite operation not in progress (line 1) invoked from whithin "session add uie 123456 [IP::client_addr].

I hope you can help me with this problem. Thanks in advance.

Andi