Hi - I recently had an issue where my new landline Sky (VoIP or internet calls where you plug your landline into the back of your Sky router) wasn't receiving incoming calls from other landlines or mobiles, but had a dial tone and could make outgoing calls fine. My broadband was working fine too and no issues accessing internet.
The solution upfront is, give it a few days for your broadband to fully activate as your number could still be porting over/being released from the registry by Openreach.
I found this out by calling Sky support and the agent helpfully had a look and saw my broadband was still activating, and my number hadn't been released by Openreach and they'd sent an email chasing, the agent advised for me to wait a few days. This was around 27 hours after my Sky broadband went live. I tried to call my landline again around 32 hours after my Sky broadband went live and bingo, my landline rings!
If you're still having issues, ring Sky support and an agent will talk you through a) asking you for pictures/video of your set-up and they'll check to ensure it's been fitted correctly, b) hard reset of your Sky router, c) assigning you a new IP address where you have to turn off your router for >10 minutes and then the agent will ask you to turn it back on again because this is a fix when this has previously been an issue for other customers, d) escalate this to the next level of support if nothing works. I don't have anything beyond d) as I didn't need this.
I'm making this post as these old threads unhelpfully didn't set out the solution to this problem and I vowed to provide some guidance to any future joiners who have the same issue (I think it'll be more prevelant with the copper network being turned off!). I've summarised the outcomes of these threads to save you time from reading them:
Thread 1, two new joiners with this issue but no report of solution: https://helpforum.sky.com/t5/Talk/Can-make-outgoing-calls-but-no-incoming-calls/td-p/4053746
Thread 2, two new joiners. Original poster contacted Sky support and probably went through with action c) above. Second poster's son was a Sky engineer who fixed her issue but didn't post the solution: https://helpforum.sky.com/t5/Talk/Landline-unable-to-receive-incoming-calls-since-Sky-broadband-acti...
Thread 3, two new joiners where they can't receive calls from a mobile where the network isn't Sky - This is why I tried ringing with a landline and different mobiles on different networks but my landline didn't ring on any of them: https://helpforum.sky.com/t5/Talk/Landline-wont-receive-incoming-calls/m-p/4031892
Thread 4, this doesn't seem to a be a new joiner and a new issue with being unable to receive incoming calls, I ignored this thread: https://helpforum.sky.com/t5/Talk/Landline-doesn-t-receive-calls/td-p/4058485
Thread 5, this poster has a copper landline, not VoIP, ignore this thread: https://helpforum.sky.com/t5/Talk/Unable-to-receive-incoming-calls/td-p/4100526
More background if it's relevant: I purchased Sky broadband that went live yesterday and as part of the switch from my old provider an Openreach engineer came round to install an Optional Network Terminal (ONT) as per Openreach retiring their copper network. Openreach engineers came a few weeks earlier to install a new line outside my property, and the engineer yesterday had to drill a hole to fit the ONT. The old Openreach master socket is redundant but Openreach don't let their engineers remove these. More on ONTs here if you're so inclined: https://www.sky.com/help/articles/optical-network-terminal-t1
