Hello,

sip registration is kept for the duration of expires value and "older one" is relative and might be something that results in unwanted behaviour. For example, if you have 2 end points for the same user, one fixed phone registering every hour and one mobile app registering every 5min, when the mobile app changes mobile network/wifi and registers again with a new contact, you may end up removing the contact corresponding to the fixed phone, instead of the previous contact for mobile app (which has an invalid IP due to migration to another network). So I would rather be very careful with removing the older contacts.

That being said, you can fetch all the contacts for a user using reg_fetch_contacts(), loop with a while through them and keep the ruid attribute for the contact you want to remove and then use unregister() for it. Here are relevant examples that can help implementing it:

  * https://www.kamailio.org/docs/modules/stable/modules/registrar.html#idm909

  * https://www.kamailio.org/docs/modules/stable/modules/registrar.html#registrar.f.unregister

If you ensure the same expires value for registrations, practically the oldest contact has the lowest value for $ulc(caller=>expires). If devices use different expires values, then you end up in the case described by my remark above. You can also test the last_modified field to decide what is the oldest contact.

Cheers,
Daniel

Greetings, 

I'm currently creating a Kamailio with registrations and i'm unsure how to use the save() function.

I want to limit the number of contacts for the AOR to 2. I also want to force the registration of new contacts even if the maximum number is reached, removing the older ones.

I saw that on opensips i could use the flags "fc2" for this but they aren't available on Kamailio's save(). I'm using the max_contacts parameter but in the docs it states the once the limit is reached, it will reject new Registers.

How can i implement the force registration behaviour here?

Best Regards,

Duarte Rocha

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Daniel-Constantin Mierla -- www.asipto.com
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