This is the strangest set of symptoms I’ve ever seen.
I assume that you have a typo and mean SPA3102 – if you have some other device, post make and model.
If the phone line it’s connected to is other than a copper pair fed from a Central Office, please post details (cable MTA, VoIP provider with locked ATA, POTS from fiber ONT, etc.)
Immediately after a failed call, what does the Info page of the SPA show for Last PSTN Disconnect Reason? If a disconnect tone was the cause, see whether temporarily setting Detect Disconnect Tone to no works around the problem.
If your POTS carrier sends caller ID as 10 digits and you are not prefixing a 1 before passing it to Flowroute, you are sending an international caller ID, which might affect either Flowroute’s or the MNO’s handling of the call. In Follow-Me for the relevant extension, try temporarily setting Change External CID Configuration to Fixed CID Value and set Fixed CID Value to a valid 11-digit number starting with 1.
Report whether answering the POTS line immediately, e.g. by temporarily setting Play Music On Hold for the Ring Group to default, works around the problem.
I am guessing that the robot you hear on your cell phone may be ‘access to voicemail from external’. However, since it might be something malicious, to test this do:
- Change your voicemail password to something you don’t use anywhere.
- Answer the follow-me call after 10 seconds, enter the area code and number of your mobile, enter the temporary password and report what happens.
- Immediately change your voicemail password back to the original value.
Report any non-voice equipment connected to your POTS line (fax machine, alarm system, etc.)
Post any special settings in your Ring Group or Follow Me (announcements, music, confirmations, etc.)
Post firmware version of your SPA3102 and the value set for Disconnect Tone.
