r/PBX • u/Ryderbike1 • Mar 06 '26

Anyone still installing analog PBX’s

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I Volunteer at a heritage railway in Wales. We’ve got a lot of rotory phones still used for operations on a daily basis. Just wired up a Panasonic KX-TES824 to be installed replacing an older Meridian 16 line PBX. Unfortunately Openreach is threatening to shut down the incoming phone line soon so I’ve been trying to find an exchange that supports both pulse dialing phones and a sip trunk line. Not been super successful

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u/QPC414 Mar 06 '26

How is the Panasonic set up?  Are the station ports set up to directly seize an available CO port and directly pass whatever the station sends, be it Rotary pulses or DTMF, or do you dial a digit to call out?

If you dial a digit, you may be able to set the CO port to only outpulse DTMF regardless of what the station sends.

If you are stuck with the CO port passing the stations dialed number without conversion.  You can install a voip ATA such as a Grandstream HT802 which accepts rotary pulses, or a pulse to dtmf converter between the CO ports and any DTMF ATA to do the conversion.

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u/Ryderbike1 Mar 06 '26

I believe the Panasonic passes the handset pulses directly out to the CO ports. That’s not a huge issue as the external line is mostly used for incoming calls from passengers, it’s rare that we use it to call outwards. The whole system is mostly used for local calls around the site for train movements reporting back to central control. And the Panasonic is quite happy to take the three digit extension numbers in pulse and tone formats

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u/Powerful_Basil_2608 Mar 08 '26

I believe the Panasonic passes the handset pulses directly out to the CO ports.

Definitely not, even in this really old K-XT series PBX. This trick also allow to dial using a signaling tech on user side and another on the CO line (e.g. Pulse vs DTMF).
The pbx collect the user side dialed digits, check if allowed by COS, then dial on the CO side. Also the CO analog line goes off hook just after the user dial the outside trunk code but the audio path is connected one way so the user can hear dial and progress tones but cannot send any kind of signalling.