Q: volume while on a phone call is too low

Hi, maureenfromoradell.  

Thank you for visiting Apple Support Communities. 

I understand that the volume is low via the receiver during a call.  Here is a troubleshooting resource that I would recommend going through when experiencing this issue.  

If you can't hear a person on a call or voicemail or if the sound quality is poor on iPhone

If the issue persists, see the section labeled Get more help.

Cheers,

Jason H.