Do you know any free softphone with popup feature for an external application?

HEllo All,
Do you know any free softphone with popup feature for an external application ?
I need when incoming call to launch a os command to open a external application / url with calledid parameter

Thank you,
Daniel

The SJphone from SJ labs is a free softphone for PC (Windows, MAC or Linux) and for a PDA

Development may have ceased — the last new release was in 2007.

https://www.voip-info.org/sjphone/