Have anyone tried re-using the old impact scs 8312/24 phones in an mbx ip? Is there anything to watch-out other than the 3-softkeys won't work as well as the shift key?

I understand I will have to use the 4532-12C module to support the phones.

Re-using the 8312/24 phones will reduce cost compared to replacing the whole system...not to mention the speaker phone issues we had with the sbx digital phones.

Need advice.
Thanks.
Alvin