Busy tone on ALE H2P phone

[rav_sk]

Dear all,

Its is case of OXO connect_REL 6.2 with 300 Open sip users. All phones are of ALE make _H2p model.
When Sip user A makes a call to Sip User B and conversation starts. At the same time third sip user C calls sip user A. Sip user C doesn't get any busy tone instead getting ringing tone just like of free user. Calling user C thinks that called user is not answering the phone, but User A is busy with another sip User-B.
But when any Noe User (20h/30h) makes a call to sip user, gets proper call waiting busy tone.
So, can we give call waiting busy tone to the sip user also.

Thanks and regards,

Ravinder Singh
Mob: +91-8711801313