Push To Talk (PTT) is similar to PMR/walkie-talkie or two-way radio, where one press the button and talk, and others in same channel/group hear speech without need to answer. Main difference between PTT and PMR/walkie talkie is that PTT use existing mobile data, but PMR/walkie talkie require its own, dedicated network.

Key advantages of PTT compared to PMR are, that it's globally available from day-1, do not require dedicated radio-frequence and run on normal android-phones, instead of expensive, dedicated handsets.

In normal PTT-call, only one person at the time can talk. Talk-time is limited, usual configurations are 30-120 seconds, which after system cancel the call so that others can talk in turn.

In addition to group- and private PTT-calls, wich are walkie-talkie type one-directional, there is special call-mode called full-dublex call, Iwhich is similar to GSM-call or skype, and both can talk simultaneously without pressing the PTT-button.

In PMR/Walkie talkie, such as VHF, there are limited number of channels. In PTT there are unlimited number of groups.

User must belong at least one group, but s/he can belong to several group also.

PTT can use any available IP (Internet Protocol) network to transmit data, including all generations mobile data networks (2G, 3G and 4G/LTE), as well as WiFi or wired internet-connection.

However MCPTT-mode - if enabled, requires LTE or fast Wifi, it do not work on 2G/3G networks.

First generation PoC, (introduced ~2004) was a system that was governed by network operaters and it worked only in cellular network, standardized by Open Mobile Alliance (OMA), project led by Nokia, Ericsson and Motorila. WT released and deployed first OMA-compliant PoC-server 2004, and successfully participated in OMA Interoperability test at 2005.

PTT is generic name covering both solutions based on telco-standards and various proprietary implementation: examples include iDEN, VHF/UHF and various IP/data-based non-standard solution.

MCPTT new global standard, which will replace legacy group communication systems, such as VHF, TETRA, P25, iDEN and others.Key-advatage is that MCPTT is based on LTE-architecture and will be available for both, goverments/public safety as well as commercial users. This market-approach drives costs down due to economies of scale. Sharing network-infrastructure with commercial users ensure adequate capacity for emergency situation, where public safety will have priority over commercial users.3GPP has been focused on network infrastructure. Client-side is left up to manufacturers to design and implement according to the market requirements.

PUSHCOM is new generation PTT system, designed for Mission Critical communication. It is backward compatible with first generation PTT systems, such as Motorola and Nokia. PUSHCOM is compliant with relevant MCPTT-specifications from 3GPP and IETF, and is designed to replace TETRA, iDEN, P25, VHF and other legacy solutions. Some features, like group-scanning, emergency-calls & state, and call priorities are functionally adopted from TETRA but technically implemented as in 3GPP Rel 13.

PUSHCOM has the following additional services:

1. Floating SOS- and PTT buttons, to allow seamless PTT-usage with other applications in Android

2. Hands-free (VOX): when activated, channel is automatically opened when user talk.

3. Call recording and playback in handset ("Say again")

4. Lone worker protection ('Man Down') - if device doesn't move, alert with location-information is raised.

5. Location Tracking, using GPS and network locationing.

6. Editable maps (based on OpenSteetMaps), allowing customer-organization to add own it's own, private point of interests, buildings, paths and roads.

7. Strong encryption (TLS 1.2, RC4 / AES 256)

8. Ambient listening: Dispatcher can silently open handset's mic for listening.

9. PIN-protected settings, to prevent end-user change settings.

10. Kiosk-mode: lock android-device to PTT-only use.

11. And more...

PUSHCOM is available as a cloud-service, and it can be installed on customers own servers or private cloud.

PUSHCOM/PTT system consist of following:

1. Smartphone with PUSHCOM client application

2. Server-software in internet (in cloud, organization server, or private cloud)

3. Network connection over mobile data or WIFI

PTT uses mobile phone networks rather than radio base stations. When PTT call is made, instead of making phone-call, voice is transmitted over data-connection, similarly to Voice over IP (VoIP), from client-application to server. Server copy audio-stream in realtime to all online-users who belong to same group. Group-members hear audio automatically from loudspeaker, without need to answer.

PUSHCOM is tested in more than 100 mobile networks around world, and it works out of the box in any network.

However, for good user-experience following are recommended network-quality parameters:

1. Volume: 250Mbytes/month/user

2. Bitrate: +128kbit/seconds/user

3. Nominal bandwith is 8kbit/s with NB-AMR codec, in backward-compatibility mode and 12kbit/s with WB-AMR codec (MCPTT mode])

4. RTT: <100 ms. Smaller is better

5. mdev (jitter): <100 ms. Smaller is better

• Android 5.1 and newer phones, tablets and computers

• iPhones and iPads with IOS version 8 or newer

• Linux systems with kernel 3.0 or later, both 32 and 64 bit versions. All distributions supported

• Embedded screen-less Linux systems having only microphone, loudspeaker and PTT button

Dispatcher is person (or machine) which Dispatch resources.

Dispatch is a procedure for assigning employees (workers) or vehicles to customers. Industries that dispatch include taxicabs, couriers, emergency services, as well as home and commercial services such as maid services, plumbing, HVAC, pest control and electricians.

With vehicle dispatching, clients are matched to vehicles according to the order in which clients called and the proximity of vehicles to each client's pick-up location. Telephone operators take calls from clients, then either enter the client's information into a computer or write it down and give it to a dispatcher. In some cases, calls may be assigned a priority by the call-taker. Priority calls may jump the queue of pending calls. In the first scenario, a central computer then communicates with the mobile data terminal located in each vehicle (see computer assisted dispatch); in the second, the dispatcher communicates with the driver of each vehicle via two-way radio.

PUSHCOM-dispatcher refers to special client software aimed for dispatching purposes.

Android-client, when installed on tablet or computer, configure itself on dispatcher mode.

Separate Linux and Windows dispatcher workstation software is available.

PUSHCOM can increase revenue due to more efficient resource allocation and save money due to cost-effective communication system compared to legacy group-communication systems, such as walkie-talkie, TETRA, AP25 or iDEN.

It will be available nation-wide from day-1, and can be used as cloud-service, so the initial costs are close to zero.

It can play a key part in workforce management and hence drive greater efficiencies to allow staffing and operational costs to be reduced.

Username is string of characters that identifies a user in the domain. Usernames have similar restrictions as email addresses: they cannot have spaces or special characters. In PUSHCOM, it is recommended to use a phone number as username in order to avoid conflicts.

User ID follows the form of: <username>@<domain>.

Nickname is either person real name, like 'John Smith', or some role name like 'Radio 1' or 'Guard 7'.

Password is set up during account creation, and user must type it on client-application upon first login.

Domain is string of characters, and similarly to usernames, it cannot contain spaces or special characters. In PUSHCOM, it is recommended to use a customer number and country code to form domain. For example customer Acme Ltd headquartered in Finland, with a customer number 101 will have a domain 101.fi.

PUSHCOM account for Acme Ltd field worker John Smith, phone +358123456, will then look like following:

• Domain: 101.fi

• Username: 358123456

• Nickname: John Smith

• User ID: 358123456@101.fi

• Password: topsecret

Each customer should have their own domain. When customers are located with their own domains, it is possible to:

1. Delegate admin-rights to customer. This is usually relevant with large customers, with several groups and lot of users. Although reseller usually manage customer's groups and users initially, it is often practical to hand admin-rights to customer who can add and remove users and groups as needed.

2. Generate customer-specific usage statistics and invoicing data.

3. Move customer & users to other server if needed. For example, customer may want to start with cloud-subscription, but later want to have server installed inside the company.

Domain should consists of two parts: <customer number>.<country-code>, for example 101.fi, where customer number (101) is assigned by the reseller, and country code is two letters indicating customer's headquarter location.

List of country-codes can be found from Wikipedia.

Customer database could be initially simple excel or google-sheet.

Please ensure that customer-number is static and not for example '=row()' function which changes when prior rows are deleted.

All CRM-systems (if used) provides unique customer-number

For example, our example customer Acme Ltd have customer number 101 and is located in Finland, so Acme's domain will be 101.fi

Acme have 3 field-workers using PUSHCOM: Alice Able, Bob Big and Charlie Cox.

Acme's PUSHCOM users could be as follows:

• Username: 358123456; Nickname: Alice Able; User ID: 358123456@101.fi

• Username: 358789012; Nickname: Bob Big; User ID: 358789012@101.fi

• Username: 358345678; Nickname: Charlie Cox; User ID: 358345678@101.fi

Terrestrial Trunked Radio (TETRA) is a professional mobile radio and two-way transceiver specification. First version of specification was published 1995. Instead of mobile network, TETRA require its own radionetwork. TETRA-frequences are usually licensed only to government bodies or organization close to government.

TETRA offer low-latency group- and private audio-service, but poor data- and location services. TETRA TCO (Total Cost of Ownership) is typically more than 50x higher than PUSHCOM service.

P25, also known as Project 25 or APCO-25 is suite of standards for digital radio communication, targeted on public safety agencies. It originates from 1990s and is mainly used in North America. P25 fills same role as TETRA in Europe, but the two are not interoprable.