A company optimizes the eSpace unified communications (UC) system using gateways (for example, eSpace U1980) and connect gateways using the Session Initiation Protocol (SIP). After the optimization, when an IP phone user (calling party) at headquarters calls an IP phone user (called party) in the branch, the called party can hear the calling party while the calling party cannot hear the called party.
Step 1 Capture the network data packets on the gateways at headquarters and in the branch to check whether the signaling is transmitted successfully and uses the same codec standard.
Step 2 Diagnose network issues. If the network environment cannot be modified, use the narrowband connection method, as described in Step3. Huawei obtained the following information from related customer engineers: In area zones, no routing is provided on the bearer network for the network where the IP phone is located. During signaling negotiation, data packets are received and transmitted through the device network. After a call is established, the audio data packets are transmitted using RTP in an end-to-end manner. The VoIP network and media network must use the gateway as the agency, to ensure that the bidirectional network channel exists between phones.
Step 3 Modify the trunk link between eSpace U1980 and eSpace U1930 to primary rate access (PRA) in E1 mode.
The network is not correctly connected between voice gateways.
Understand the customer's network architecture before planning a solution for the customer and ask the customer to perform a migration test before the formal migration.