I am using FreePBX with Grandstream phones and Commercial EPM. I have to edit the base file to change the ports, EPM does not (unfortunately) take the correct port for grandstream templates…i wish it did.
I have Grandstream GXP in use with Commercial EPM for testing, and can confirm that EPM writes configs properly for chan_sip and PJSIP using the correct port.
To clarify my earlier comment, commercial EPM does not set the right port IF you are using sip-tls and srtp. I think it work fine if you are not encrypting.
sorry about the confusion.
Correct EPM doesnt handle SRTP or TLS except for Sangoma phones at this time.