Keep established PBX users
Retain the extensions and calling habits that still support daily work.
Modernize your PBX without replacing everything at once.
Keep a traditional PBX and its established extensions in service while introducing SIP trunks, IP calling and new users around it. Modernize external connections in phases and validate coexistence before each cutover.
The migration decision
Keep what works while the network evolves.
Many organizations still depend on existing extensions, numbering and trunk arrangements even when new sites or SIP services are being introduced.
A coexistence design avoids tying every improvement to one system replacement. OpenVox gateways create controlled analog, digital and SIP paths between the current PBX and the target voice environment.
Add new trunks or IP users
Introduce SIP connectivity, IP extensions or another site without forcing an immediate core replacement.
Move by business priority
Separate trunk, site and endpoint migration into manageable project phases.
Coexistence architecture
Use the interface that matches the existing PBX.
FXO connects analog PBX lines, digital gateways or DTU modules connect E1/T1 services, and SIP trunks link the environment to IP-PBX, softswitch or IMS systems.
- 01Traditional PBX
Existing extensions and numbering
- 02Analog or E1/T1
Current trunk interfaces
- 03iAG800 V2 / DGW-L302
Analog FXO or digital trunk boundary
- 04SIP / IP-PBX
Target voice core
- 05New users or sites
IP phones and remote locations
Keep established PBX users
Retain extensions and calling behavior that still support daily work.
Match the existing interface
Choose analog, digital or SIP interworking from the actual PBX boundary.
Prove coexistence before cutover
Test inbound, outbound, internal and cross-system calling behavior.
Move from PBX inventory to controlled coexistence.
Document the present system, select the correct interworking path, validate calls and migrate only the elements included in each phase.
Inventory
Record PBX model, trunks, extensions, numbering and required services.
Select interfaces
Match analog, digital or SIP roles to the existing network.
Validate coexistence
Test inbound, outbound, internal and cross-system calling behavior.
Migrate in phases
Move trunks, users or sites according to operational timing.
Combine analog, digital and SIP interworking where required.
Product selection follows the existing PBX interfaces, trunk capacity, target IP system and migration sequence.
Verified interfaces for coexistence.
Based on OpenVox UCP, analog gateway and digital trunk documentation.
FXO interworking
OpenVox analog gateways and modules connect analog PSTN lines and PBX interfaces to SIP systems.
Proof chips
- ANALOG
E1/T1/J1 access
Documented digital products provide selectable trunk and signaling options.
Proof chips
- DIGITAL
IP voice interworking
UCP supports standard SIP trunks for IP-PBX, softswitch and IMS environments.
Proof chips
- SIP
Behavior validated before cutover
Numbering, signaling, call routing and service requirements are confirmed during solution design.
Proof chips
- PROJECT FIT
Modernize your PBX without replacing working infrastructure.
Share the PBX model, trunk types, extension estate and target SIP system. OpenVox can define the analog, digital and SIP interworking roles for a controlled transition.