GDPR seems quite clear that if you are recording calls, video and/or audio, you must get consent.
The GDPR requires that your have a legal basis for processing personal data. Consent is a legal basis but there are others.
With respect to note taking, the GDPR only applies to “personal data wholly or partly by automated means and to the processing other than by automated means of personal data which form part of a filing system or are intended to form part of a filing system.”
So, if they notes are not about an individual (and many B2B phone calls will not be) or are neither automated nor filed, the GDPR does not apply. If they are captured by the GDPR, you need to have a legal basis for the notes. Again, consent is one but it is not the only one.