Ghost calls are a known problem with a combination of some routers & handsets, there is a fix, but only TalkTalk can apply this. I have asked one of TalkTalk's support to pick your thread up and investigate it for you.
They aim to respond within 48 hours (Monday - Friday) excluding Bank Holidays, but if more urgent you can always try the Service Centre on 0345 172 0088. The posts are responded to in time/date order, oldest first.
