E-PCO Extended - Protocol Configuration Options
E-PCO (Extended – Protocol Configuration Options) are a means by which the device and the network gateway (e.g. GGSN, P-GW, UPF) can indirectly exchange information with one another. This information could relate to configuration parameters, error codes, message delivery or event reporting. As an example, E-PCO is routinely used to deliver DNS Server addressing to the device, as well as P-CSCF (Proxy – Call Session Control Function) addressing in support of voice services. E-PCO is exchanged with the device as a payload of NAS (Non Access Stratum Signalling) and also transported in the core network as a payload of protocols such as GTPv2-C (GPRS Tunnelling Protocol version 2 – Control) or HTTP/2 (using JSON). Note that the concept of E-PCO is the same as PCO, but the total permitted payload of E-PCO is significantly larger.
