My partner and I have been together for 2 and a half years. He has a 3 and a half year old who lives with us full time and has limited access with his mother. So I play quite a big role in his sons life.
When we first started talking and going on dates, he was still sleeping with his ex (mother of his son) which I didn't find out about until we officially got into a relationship. Once we were in a relationship, he used to go round to see his son through the week but didn't tell me that's where he was going (at the time, his son lived with the mother and he had him weekends) and if she called or text asking him to pick her up or take her somewhere he would, but again, didn't tell me about this. She then used to message me saying they were sleeping together while he's with me which he denied and I didn't believe he did. However at the time, a lot of conversations between them were over the phone.
Since then, things have been a nightmare with his sons mother and he was removed from her care and put into my partners. All conversations were over texts for about a year. But recently, he's started ringing her or she rings him instead to have the conversations aboit their son. But he takes or makes the phone calls in the back garden. I don't know if I'm just being paranoid because of everything at the start or whether it is a bit odd that he takes the calls as far away from me earshot as he can.
I have a son, there have never been any issues between myself and his father, yet we still keep most our conversations over text and if we do talk on the phone, I certainly don't take it outside or in another room. I'll sit right there in front of my partner on the phone to my child's father.