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Compare essentials or all specifications. Unknown values stay visible when showing differences.
How to read this comparison
SIP accounts are registrations, not simultaneous calls. Programmable keys count assignable positions across pages, not just physical buttons. Conference capacity and encryption depend on firmware and configuration.
No is an explicit negative; Unknown means unresolved evidence; Not applicable means the field does not apply. An optional adapter is an extra accessory. Open Evidence for model scope, source sections and qualifications.
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| Specification | Grandstream GXP2135 15 of 23 specifications recorded Lifecycle: Unknown Record reviewed: 2026-09-11 | AudioCodes C450HD 9 of 23 specifications recorded Lifecycle: Unknown Record reviewed: 2026-09-29 |
|---|---|---|
| Calling | ||
| SIP accounts / linesDifference | 4EvidenceManufacturer specification Grandstream GXP2135 datasheetSection: Page 2 — Feature Keys: SIP accounts Review note: SIP accounts are counted here; this phone has more line appearances than accounts. Evidence reviewed: 2026-09-11 Applies to: Grandstream GXP2135; currently linked manufacturer datasheet. | Unknown |
| Programmable keysDifference | 32EvidenceManufacturer specification Grandstream GXP2135 datasheetSection: Page 1 — BLF / speed-dial keys Review note: Digital BLF/speed-dial capacity includes on-screen pages; it is not a count of physical keys. Evidence reviewed: 2026-09-11 Applies to: Grandstream GXP2135; currently linked manufacturer datasheet. | 8EvidenceManufacturer specification C450HD IP PhoneSection: C450HD Features > up to 8 programmable on-screen keys Evidence reviewed: 2026-09-29 |
| Local conference participantsDifference | 4EvidenceManufacturer specification Grandstream GXP2135 datasheetSection: Page 2 — Telephony Features Evidence reviewed: 2026-09-11 Applies to: Grandstream GXP2135; currently linked manufacturer datasheet. | Unknown |
| Display | ||
| Display sizeDifference | 2.8 inEvidenceManufacturer specification Grandstream GXP2135 datasheetSection: Page 2 — Graphic Display Evidence reviewed: 2026-09-11 Applies to: Grandstream GXP2135; currently linked manufacturer datasheet. | 5 inEvidenceManufacturer specification C450HD IP PhoneSection: C450HD Features > 5-inch colour TFT screen Evidence reviewed: 2026-09-29 |
| Display resolutionDifference | 320 x 240EvidenceManufacturer specification Grandstream GXP2135 datasheetSection: Page 2 — Graphic Display Evidence reviewed: 2026-09-11 Applies to: Grandstream GXP2135; currently linked manufacturer datasheet. | 1280 x 720EvidenceManufacturer specification C450HD IP PhoneSection: C450HD Features > 1280 x 720 screen Evidence reviewed: 2026-09-29 |
| Colour display | YesEvidenceManufacturer specification Grandstream GXP2135 datasheetSection: Page 2 — TFT color LCD Evidence reviewed: 2026-09-11 Applies to: Grandstream GXP2135; currently linked manufacturer datasheet. | YesEvidenceManufacturer specification C450HD IP PhoneSection: C450HD Features > colour TFT screen Evidence reviewed: 2026-09-29 |
| TouchscreenDifference | Unknown | YesEvidenceManufacturer specification C450HD IP PhoneSection: C450HD Features > touch screen interface Evidence reviewed: 2026-09-29 |
| Connectivity | ||
| Ethernet | GigabitEvidenceManufacturer specification Grandstream GXP2135 datasheetSection: Page 2 — Network Interfaces Evidence reviewed: 2026-09-11 Applies to: Grandstream GXP2135; currently linked manufacturer datasheet. | GigabitEvidenceManufacturer specification C450HD IP PhoneSection: C450HD Features > GbE support Evidence reviewed: 2026-09-29 |
| Power over Ethernet | YesEvidenceManufacturer specification Grandstream GXP2135 datasheetSection: Page 2 — Network Interfaces / Power Evidence reviewed: 2026-09-11 Applies to: Grandstream GXP2135; currently linked manufacturer datasheet. | YesEvidenceManufacturer specification C450HD IP PhoneSection: IP Phone Series Highlights > PoE or external supply Evidence reviewed: 2026-09-29 |
| Wi-FiDifference | Unknown | Unknown |
| Wi-Fi standardDifference | Unknown | Unknown |
| BluetoothDifference | Built inEvidenceManufacturer specification Grandstream GXP2135 datasheetSection: Page 2 — Bluetooth Evidence reviewed: 2026-09-11 Applies to: Grandstream GXP2135; currently linked manufacturer datasheet. | Unknown |
| Bluetooth versionDifference | Unknown | Unknown |
| USB portsDifference | Unknown | Unknown |
| Accessories | ||
| Headset interfacesDifference | EHS, RJ9EvidenceManufacturer specification Grandstream GXP2135 datasheetSection: PDF page 2: Auxiliary Ports RJ9 headset jack (allowing EHS with Plantronics headsets) Review note: Port and EHS mode only; exact headset, cable, and call controls require separate compatibility evidence. Evidence reviewed: 2026-09-12 | USBEvidenceManufacturer specification C450HD IP PhoneSection: C450HD Features > USB headset support Evidence reviewed: 2026-09-29 |
| Expansion modulesDifference | Unknown | Unknown |
| Physical | ||
| Wall mountableDifference | YesEvidenceManufacturer specification Grandstream GXP2135 datasheetSection: Page 2 — Base Stand / Wall Mountable Review note: Wall-mount accessory is sold separately. Evidence reviewed: 2026-09-11 Applies to: Grandstream GXP2135; currently linked manufacturer datasheet. | Unknown |
| Audio | ||
| HD voiceDifference | YesEvidenceManufacturer specification Grandstream GXP2135 datasheetSection: Page 1 — HD audio / Page 2 — Voice Codecs Evidence reviewed: 2026-09-11 Applies to: Grandstream GXP2135; currently linked manufacturer datasheet. | Unknown |
| Full-duplex speakerphone | YesEvidenceManufacturer specification Grandstream GXP2135 datasheetSection: PDF page 1: full duplex-; full-duplex speakerphone wording continues on the next extracted line Evidence reviewed: 2026-09-12 | YesEvidenceManufacturer specification C450HD IP PhoneSection: IP Phone Series Highlights > full duplex speakerphone Evidence reviewed: 2026-09-29 |
| Audio codecsDifference | Unknown | Unknown |
| Software | ||
| Operating systemDifference | Unknown | Unknown |
| Security | ||
| TLS signallingDifference | YesEvidenceManufacturer specification Grandstream GXP2135 datasheetSection: Page 2 — Security Evidence reviewed: 2026-09-11 Applies to: Grandstream GXP2135; currently linked manufacturer datasheet. | Unknown |
| SRTP media encryptionDifference | YesEvidenceManufacturer specification Grandstream GXP2135 datasheetSection: Page 2 — Security Evidence reviewed: 2026-09-11 Applies to: Grandstream GXP2135; currently linked manufacturer datasheet. | Unknown |
Compatible phone systems
The indicator shows whether a compatible configuration path is documented, or whether the result still needs verification. A not-listed result does not mean technically incompatible. It does not replace checking the provider firmware branch, tenant, network and feature requirements.
3CX V20
Listed firmware applies to 3CX V20. Cloud or remote phones need a router phone or SBC. Recheck the current provider release before deployment.
Needs verification Not on reviewed list
Evidence reviewed: 2026-09-11
Sources and scope
Grandstream GXP2135. Current provider lists only. Not listed does not establish technical incompatibility. Historical 3CX V18 firmware and configuration material is not treated as current V20 support. Regional availability, hardware revisions and accessories remain unverified. No tenant or device was tested.
- 3CX V20 phone firmware
V20 scope statement and complete Phone Firmware table; no Grandstream or GXP row
Not reviewed
Zoom Phone
Yealink phones require Zoom-specific firmware. A certification entry does not confirm every feature or regional deployment.
Needs verification Not on reviewed list
Evidence reviewed: 2026-09-11
Sources and scope
Grandstream GXP2135. Current provider lists only. Not listed does not establish technical incompatibility. Historical 3CX V18 firmware and configuration material is not treated as current V20 support. Regional availability, hardware revisions and accessories remain unverified. No tenant or device was tested.
- Zoom Phone certified hardware
Desk phones > Grandstream exact-model table; the GXP model is absent; the page directs owners of unlisted models to Grandstream if assisted provisioning fails
Not reviewed
Microsoft Teams SIP Gateway
This is SIP Gateway compatibility, not native Teams-phone certification. Use the gateway provisioning path and approved firmware; confirm tenant licensing, policies and network requirements.
Needs verification Not on reviewed list
Evidence reviewed: 2026-09-11
Sources and scope
Grandstream GXP2135. Current provider lists only. Not listed does not establish technical incompatibility. Historical 3CX V18 firmware and configuration material is not treated as current V20 support. Regional availability, hardware revisions and accessories remain unverified. No tenant or device was tested.
- Microsoft Teams SIP Gateway plan
Compatible devices table; no Grandstream vendor or GXP model row
Not reviewed
Specifications may vary by region, hardware revision, firmware, or optional accessory. A review date or recorded field is not a compatibility guarantee. Follow each product’s official sources before purchasing or deploying.
158 phones found
Unknown means not yet verified, not No.
Before choosing a phone
Treat this comparison as a research aid, not a compatibility or purchasing guarantee. Confirm regional variants, firmware support, platform certification, power requirements, accessories, lifecycle status, and current availability with the manufacturer and your phone-system provider.