[HELP] Asterisk/Zaptel answers *outbound* POTS calls

My question is:

Is there some way to to configure Asterisk/Zaptel so that it only answers the POTS line when there is an incoming ring (and not on off-hook or DTMF tone dialing)?

I’ve searched around quite a bit, and have not found a solution anywhere.

Is there a better forum or mailing list where I should post this question?

Here is specific information on my setup and the problem I am encountering:

I am running Asterisk on Gentoo Linux, using a low cost generic Zaptel compatible modem to plug a POTS line into Asterisk. I am using Asterisk as a glorified answering machine, mostly to screen out telemarketers and convert voicemails to emails. Incoming calls that get past Asterisk are routed via SIP to a HandyTone-286 which rings my desk phone. All of this is working well.

The problem is that I have other POTS phones (in other rooms) plugged into my single POTS line. When I dial out on one of these POTS phones, Asterisk/Zaptel hears the DTMF number I am dailing out. Asterisk/Zaptel assumes that the DTMF number is an incoming call and, consequently, Asterisk “answers” (interrupts) at the beginning of every outgoing call I make from my POTS phones. (This is probably quite funny from a third person point of view, but it is quite frustrating from a first person point of view.)

Relatedly, if I answer a call on my SIP HandyTone-286 phone, and then switch to another phone during the call (hanging up the HandyTone phone in the process), Asterisk/Zaptel will eventually detect that the POTS line is off-hook, and Asterisk will decide that the line is off-hook because there is an incoming call that Asterisk needs to service, and Asterisk will again interrupt my ongoing call.

I have created a minimal workaround for this problem. When Asterisk interrupts, I can press 5 to send Asterisk into 3600 second delay. But I would really like to find a better solution where Asterisk will only answer the call on incoming rings.

Thank you for your attention.