The solution developed by the software vendor is for end point to endpoint encrypted communication ( the vendor has used several open-source tools/platforms to).  vendors has delivered the application for us to test and have asked us to validate if the communication is encrypted, we would like to validate on the following cases  

1. is communication of voice between endpoints to server and endpoints to endpoints are encrypted  ( app is used in endpoints- mobile devices)
2. is video communication between endpoints to endpoints are encrypted
3. is messages/chat  between endpoints to endpoints ( mobile to mobile ) is encrypted

please suggest is there different ways to check or validate communications are encrypted for above 1 to 3.

VOIP Software development product vendor has reverted with the following
1. All the communication between the app and server for REST interface is over HTTPS that encrypts data between device and user,

2.  The  RTP Payload of calls is being encrypted with AES 256 Encryption

3. the above can be validated through wireshark
Next,  they are planning to implement SRTP. SRTP that provides an additional layer of security

Sir, so as per the software developer vendor used TLS for channel encryption and  RTP Payload of calls is being encrypted with AES 256 Encryption.

I should be asking them test/validation demo for the above in additional should ask them how about the encryption of video and data and once SRTP implemented then demo the same.

thanks,  the vendor says  implemented "RTP Payload of calls is being encrypted with AES 256 Encryption" , please help me understand on the following

1. does it mean RTP Payload of video encryption is yet to be implemented,
2. and he is not mentioned about messages
if my above understanding is correct I will be asking them as following
for now demonstrate on
1. channel encryption
2. calls encryption
and readiness duration of the migration to SRTP
please suggest

as per the software vendor following are the encryption algorithm used for the product development:
for voice -> encryption algorithm = AES + RSA+SRTP
for video -> encryption algorithm = AES + RSA + SRTP
for data ( file transfers) -> HTTPS (TLS 1.3)
for chat -> encryption algorithm = AES

thank you all, before closing this question, is it possible to test/validate encryption form for all the various channels (voice, video , chat and data transfer) through Wireshark.