This maybe a QoS issue.
The Welltech CPE has a DSCP function can let you define a DSCP code for QoS.
The welltech CPE can help user define the DSCP code by below commands to define the DSCP code for RTP media or Call signal.
[tos -rtptype x] or [tos -sigtype x], where x is the DSCP code.
Differentiated Services (DiffServ) is a new model in which traffic is treated by intermediate systems with relative priorities based on the type of services (ToS) field. Defined in RFC 2474 and RFC 2475, the DiffServ standard supersedes the original specification for defining packet priority described in RFC 791. DiffServ increases the number of definable priority levels by reallocating bits of an IP packet for priority marking.
The DiffServ architecture defines the DiffServ (DS) field, which supersedes the ToS field in IPv4 to make per-hop behavior (PHB) decisions about packet classification and traffic conditioning functions, such as metering, marking, shaping, and policing.
TOS/DiffServ (DS) priority function can discriminate the Differentiated Service Code Point (DSCP) of the DS field in the IP packet header, and map each Code Point to a corresponding egress traffic priority. As per the definition in RFC2474, the DS field is Type-of-Service (TOS) octet in IPv4. The recommended DiffServ Code Point is defined in RFC2597 to classify the traffic into different service classes. The mapping of Code Point value of DS-field to egress traffic priorities is shown as follows.
Please refer to RFC standard documents for more information about what is DSCP.
So, this code is only for router to define the priority of packets, the higher DSCP code the higher priority.
The QoS effort is still based on the router, so your router must define the QoS police based on the DSCP.
If you just connect your CPE under the Public IP or PPPoE, the DSCP is not usful.
We recommend you set the voice prarmeters to avoid the [Network Congestion] problem.
Below are the suggestions:
*** Change the voice codec to G723 or G729
*** Adjust the higher sample rate with [voice -send G723] or [voice -send G729] command.
*** Adjust the lower jitter buffer with [voice -mindelay] and [voice -maxdelay] command.