Answered call being showed "missed call" on other devices with same SIP

Question

I'm using Zoiper for my company call center. There are many devices using same SIP on Zoiper to answer calls. When a device answers a call it shows "answered" on that devices but "missed call" on other devices with same SIP. How can I fix this? I want an answered call is showed "answered" on all devices with the same SIP no matter which one answered.

Comments

Hello,

There is no way for us to tell whether the call has been answered or not, we can just show it as "missed" when the server sends the "cancel" or not show it at all since the RFC's do not explicitly say what should be done. Other situations require more customizing.  However our customers prefer to see "missed" notifications.