One extension number on two devices

how i can use the same extension number on two sip phones so if call extension number both of them will ringing and if one of them busy the other will answer?
this scenario as installing two sip phones in hotels room with one extension number
please help

You can’t do this directly. The common practice for this is to create two extensions. Their numbers would be outside the regular extension sequence.

You’d create a ring group numbered inside the regular extension sequence.

You place both the new phones inside the the new ring group and use the ring group extension as the published number.

Being on one phone would not busy the second line.

BF

I believe you can also use device & user mode. Then you can have multiple devices with the same user (extension).