Here is my scenario. I am in the office lab and all equipment( TUTORIAL LICENSES ACTIVATED) is on LAN
SITE A: OS7400 ver 4.75 with SIP trunks and POTS
SITE B: OS7070 ver 4.94 with YEALINK SIPphones and Keysets
the 2 sites are SPNet linked.
1.From site B, I cannot dial out on the SIP trunks from the Keysets or the Yealink T21P. Keysets can dial out successfully on POTS trunks but SIPphone drops out.
2.From site B a call to site A by the YEALINK rings the other end's extension but there is no audio even vice-versa.
Please assist such that I can make successful calls from site B

I would upgrade the OS7400 to match the OS7070.

Did you set the IP of the OAS/MGI card in the OS7400?

Is your spent set "no mGI" on or off?