Q: texting not working while on the phone .

Do you have a GSM iPhone? If not, it only works as you described.

probably cdma (verizon like) phone... cdma = outdated aged tech.

call your carrier.

What carrier are you using and where are you using it or just ask your carrier.

iOS: Understanding cellular data networks

It's CDMA, so what you describe eariler in your post is correct. CDMA cannot call and use data at the same time, only GSM can do this.

There you go Sprint is CDMA as it does not rely on a SIM card.

You should still be able to send texts while you're on the phone. If you're trying to send a picture message (MMS) while on the phone (using cellular data) this is normal that you cannot send while on a call (only GSM devices, AT&T for example, can use cell data and make calls at the same time) For this reason, GSM is better. GSM is not always better where you're located, pricing of plans, etc.

You can use WiFi while on calls though. So if you're trying to send an iMessage and you're connected to WiFi you can do so while on a call.

Just remember CDMA (Verizon, Sprint) cannot use cell data while making a call. This is normal behavior.

I hope this helps.

cdma carriers do rely on sim cards if the phone has LTE. Lte = gsm tech.