How do I initiate a line test?

[#1]

I looked at https://www.plus.net/help/report-a-problem/broadband/ and there's no way to log a broadband issue online (I can't send SMS)

I also found the contact number 0800 432 0200 but that just tells me it doesn't recognise my landline number and hangs up on me without giving me any other options.

All I want to do is run a line test, because I can't ping my router's public IP from where I'm travelling and I need to access my server (port forwarding configured).

Once upon a time you could start a problem ticket and it would go through interactive troubleshooting and then run a line test.  

[#2]

Which router are you using?

The standard PN ones do not respond to external pings.

[#3]

I'm using a Mikrotik RB750 with a BT Openreach ADSL modem. So I've configured it to respond to ping.
I'm not sure if the issue is in the BT line to the house, the 25yr old phone cables in the house or the modem or the router.

[#4]

Which BT Openreach ADSL modem.?

Do you have a static IP?

What did you configure to respond to pings?

Can't see how a line test will answer any of your questions.

[#5]

@banjo67xxx 

You can report a fault using this link https://faults.plus.net but as previously stated a line test may not be your answer

Using say no to 0870 I find +44 345 140 0200  as the number from abroad

HTH

[#6]

To initiate a Plusnet line test: Text "PHONE <landline no.>" to 07800 008121

To initiate a BT line test: Text "PHONE <landline no.>" to 61998