New IP DECT from Grandstream DP715 / DP710



An already well-known manufacturer of VoIP telephony devices has entered the market with a budget solution for wireless phones. The solution consists of two positions - a DECT handset complete with a base station (it is also a stand for the device and charging) is called DP715. Overview under the cut.



A DECT handset without base complete with a charging stand is called the DP710.



The fact is that up to 5 handsets can be registered to one base, each either with a personal number or in a group with other handsets. Phones in groups can ring at the same time or use one line, like analog phones connected in parallel, calls to them can also be received either in turn or simultaneously. Handsets, of course, can transfer calls, set up call forwarding, do not disturb, there is a speakerphone, etc.

It is also interesting that each handset can be registered at 4 bases simultaneously. This will allow the phones to work, even if they are out of the reach of their home base.
I must say right away that this is not a full-fledged DECT system for enterprises, which provides seamless transfer of conversation from base to base, but how to organize (with certain restrictions) mobile communications over a larger territory, I will describe in more detail below.

Short review


Base

Tabletop. There is an indication of power, network availability, registration and employment.



At the back, unfortunately, there is no switch to connect the computer, nor additional FXS or FXO interfaces.



If anyone is interested in the web interface for configuring the database, everything can be viewed here:
dp715_gui.zip

A tube


The tube is completely plastic, fairly lightweight, fits comfortably in your hand, but is a bit long to fit in any pocket. The keys are all in reach of the thumb, not small. The backlight is blue.
Batteries included, regular AAA finger batteries, 500mAh
C control is simple and convenient: the
left key is the phonebook entry, the right key is in the menu.
4-way up-down key - access to the logs of dialed and unanswered calls, to the left - direct access to other handsets on this base (Intercom), to the right - call transfer (Recall).
If you press the green key a second time, the conversation is through the speaker.

The Russian language is supported, the display shows the name of the handset, which the user configures and followed by a digit from 1 to 5 - the handset number in the database (Intercom number).



Considerations for use cases


Initially, of course, the DP71X tubes are ideal for home, large home, detached small offices, warehouses. A complete configuration is considered one base with five tubes. However, the size of the territory covered by one DECT base is limited to 50 meters in circumference.

I want to tell you how to increase the coverage area if you place several base stations across the territory. To do this, the handset must be registered at each of the bases under auxiliary numbers and dial up.
For example, we need to register a subscriber with number 101 on several bases.

We put the phone on our base at number 101, on the second base in second place as 2101, in third - in third place as 3101 and so on:
Register at all bases



and set auto-selection.
Then in IP PBX we set call forwarding from one number to another by the condition of unavailability. This will provide dialing to the handset, no matter in which zone it is.

In Asterisk, for example, if you use FreePBX, this can be done like this:
On auxiliary numbers, configure the Outbound CID of the main number for correct display:
and configure forwarding when unavailable to the next auxiliary number:



What may be the features of such a system:


Firstly, of course, when you switch from the zone of one base to another, the conversation will end as soon as the handset completely loses the signal of the first base, i.e. Handover will not work. Will have to call back.

Secondly, if you want to configure such functions as “do not disturb”, immediate call forwarding on the phone, you need to do this only after making sure that your handset has chosen its own, first base (the number should appear on the display after the handset name).

It is necessary to set up call forwarding based on non-response or busy at both the main and auxiliary numbers of the handset. In the same Asterisk, I think, all this can be solved if desired with the help of additional macros.

If IP ATC requires licensing the number of SIP subscribers, then you must not forget that the total number of licenses required is the product of the number of handsets and the number of bases.

A significant drawback may also turn out to be that DECT bases are not hung on the walls, they are also chargers for the handset and thus are tied to the workplaces of employees. It can be difficult to mark them as required to cover the entire territory, so this solution is not always applicable. However, in hotels / hospitals, where maid / nursing rooms are located on each floor, or for security, where posts are distributed across the territory, this may turn out to be a good budget solution.

Pricing Summary
. DP715 costs $ 85. DP710 costs $ 47.
Such a system can maximally consist of 5 mobile subscribers and four DECT bases
and cost $ 85 x4 + $ 47 = $ 387. Not bad, what do you think?

I will add that the bases also support tubes of other manufacturers using the GAP protocol. I tested the Siemens handset from the C595IP kit. All the main functions - displaying ID, transferring calls - everything worked perfectly.

Specifications:


Key features
• The DECT base station allows you to simultaneously register up to 5 DECT handsets and conduct up to 4 parallel conversations
• If several handsets use the same SIP account, the Hunting Group supports the following operating modes:
- Line mode: all phones ring consecutively in a pre-configured order;
- Group line mode: all phones ring simultaneously and use one line according to the principle of analog
phones;
- Parallel mode: all phones ring simultaneously, and after one telephone answers, the remaining free phones can be used for further calls.
• Advanced telephony features, including caller’s number reflection, incoming
call
notification
, three-way conference call, call transfer, call forwarding, barring of incoming calls,
new voice message indication, answering machine, voice prompts with multi-language support, flexible
dialing
order
• Support for complex voice codecs, including G.711, G 723.1, G 729A / B, G.726 and iLBC
• Communication security through the use of SIP protocols via TLS and SRTP
• Automatic provisioning using HTTP / HTTPS / TFTP / AES-256
• Duration of calls - 10 hours, standby time - 80 hours, charging time - 16 hours

Specification






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