Well this is another wierd one. SX50 system connected to a T1 via a channel bank.(an Adtran, I dont remember the model) 4 Ground start lines and has been working good for years. No problem calling out but we can only answer an incoming call if we hit the answer button while the trunk is ringing. If you hit answer between rings it just keeps ringing. I have tried it at the RJ21 with a butt set and have the same problem.If you stay offhook till the next ringing cycle it will answer as soon as the ring voltage hits. So far I cant convince the telco that they have a problem. When they come out and test at the RJ21 they clip there butt set tip to ring then apply a quick ground and go off hook at the same time to answer. It works every time that way. I have never applied a ground to answer a call on a ground start line but the telco says that is the way it should be done. They have changed the channel bank twice and I changed the trunk card in the system and even changed the entire system.
Three questions in this long post. Does the SX50 apply a ground to answer on ground start lines?
Next question, Have I been testing ground start lines the wrong way for over 30 years?? I am thinking something in the channel bank is not programmed like it should be. Anyone know what in the programming I should tell them to check.

Thanks